So I found some interesting results.

The first login, which triggers the artifacting:

https://pastebin.com/raw/8vj1qVeR

The second login, which is normal:

https://pastebin.com/raw/bjXi7BAA

The diff between the two:

https://pastebin.com/raw/f0pwCxFi

Now I try to break down the diff:

The first diff:

(EE) /dev/dri/card0: failed to set DRM interface version 1.4: Permission denied

I don’t know why drm would fail on the first login.

The second:

(WW) Falling back to old probe method for modesetting

Then the diff becomes really big. The second login seems to run modeset properly:

(==) modeset(G0): Depth 24, (==) framebuffer bpp 32 (**) modeset(G0): Option "AccelMethod" "None" (==) modeset(G0): RGB weight 888 (==) modeset(G0): Default visual is TrueColor (**) modeset(G0): glamor disabled (II) modeset(G0): ShadowFB: preferred YES, enabled YES (II) modeset(G0): Double-buffered shadow updates: off (II) modeset(G0): Output eDP-1-1 has no monitor section (II) modeset(G0): Output HDMI-1-1 has no monitor section (II) modeset(G0): EDID for output eDP-1-1 (II) modeset(G0): Manufacturer: LGD Model: 4b9 Serial#: 0 (II) modeset(G0): Year: 2015 Week: 0 (II) modeset(G0): EDID Version: 1.4 (II) modeset(G0): Digital Display Input (II) modeset(G0): 6 bits per channel (II) modeset(G0): Digital interface is DisplayPort (II) modeset(G0): Max Image Size [cm (II) modeset(G0): Gamma: 2.20 (II) modeset(G0): DPMS capabilities: StandBy Suspend Off (II) modeset(G0): Supported color encodings: RGB 4:4:4 YCrCb 4:4:4 (II) modeset(G0): First detailed timing is preferred mode (II) modeset(G0): Preferred mode is native pixel format and refresh rate (II) modeset(G0): redX: 0.580 redY: 0.350 greenX: 0.340 greenY: 0.560 (II) modeset(G0): blueX: 0.155 blueY: 0.125 whiteX: 0.313 whiteY: 0.329 (II) modeset(G0): Manufacturer's mask: 0 (II) modeset(G0): Supported detailed timing: (II) modeset(G0): clock: 138.7 MHz Image Size: 344 x 194 mm (II) modeset(G0): h_active: 1920 h_sync: 1968 h_sync_end 2000 h_blank_end 2080 h_border: 0 (II) modeset(G0): v_active: 1080 v_sync: 1083 v_sync_end 1088 v_blanking: 1111 v_border: 0 (II) modeset(G0): Supported detailed timing: (II) modeset(G0): clock: 111.0 MHz Image Size: 344 x 194 mm (II) modeset(G0): h_active: 1920 h_sync: 1968 h_sync_end 2000 h_blank_end 2080 h_border: 0 (II) modeset(G0): v_active: 1080 v_sync: 1083 v_sync_end 1088 v_blanking: 1111 v_border: 0 (II) modeset(G0): 9HG62�156WF6 (II) modeset(G0): Unknown vendor-specific block 0 (II) modeset(G0): EDID (in hex): (II) modeset(G0): 00ffffffffffff0030e4b90400000000 (II) modeset(G0): 0019010495221378eaa1c59459578f27 (II) modeset(G0): 20505400000001010101010101010101 (II) modeset(G0): 0101010101012e3680a070381f403020 (II) modeset(G0): 350058c21000001a5c2b80a070381f40 (II) modeset(G0): 3020350058c21000001a000000fe0039 (II) modeset(G0): 48473632803135365746360a00000000 (II) modeset(G0): 0000413196001000000a010a20200058 (II) modeset(G0): Printing probed modes for output eDP-1-1 (II) modeset(G0): Modeline "1920x1080"x60.0 138.70 1920 1968 2000 2080 1080 1083 1088 1111 +hsync -vsync (66.7 kHz eP) (II) modeset(G0): Modeline "1920x1080"x59.9 138.50 1920 1968 2000 2080 1080 1083 1088 1111 +hsync -vsync (66.6 kHz d) (II) modeset(G0): Modeline "1920x1080"x48.0 111.00 1920 1968 2000 2080 1080 1083 1088 1111 +hsync -vsync (53.4 kHz e) (II) modeset(G0): Modeline "1680x1050"x60.0 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsync (65.3 kHz d) (II) modeset(G0): Modeline "1680x1050"x59.9 119.00 1680 1728 1760 1840 1050 1053 1059 1080 +hsync -vsync (64.7 kHz d) (II) modeset(G0): Modeline "1600x1024"x60.2 103.12 1600 1600 1656 1664 1024 1024 1029 1030 +hsync +vsync (62.0 kHz d) (II) modeset(G0): Modeline "1400x1050"x60.0 122.00 1400 1488 1640 1880 1050 1052 1064 1082 +hsync +vsync (64.9 kHz d) (II) modeset(G0): Modeline "1280x1024"x60.0 108.00 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync (64.0 kHz d) (II) modeset(G0): Modeline "1440x900"x59.9 106.50 1440 1520 1672 1904 900 903 909 934 -hsync +vsync (55.9 kHz d) (II) modeset(G0): Modeline "1280x960"x60.0 108.00 1280 1376 1488 1800 960 961 964 1000 +hsync +vsync (60.0 kHz d) (II) modeset(G0): Modeline "1360x768"x59.8 84.75 1360 1432 1568 1776 768 771 781 798 -hsync +vsync (47.7 kHz d) (II) modeset(G0): Modeline "1360x768"x60.0 72.00 1360 1408 1440 1520 768 771 781 790 +hsync -vsync (47.4 kHz d) (II) modeset(G0): Modeline "1152x864"x60.0 81.62 1152 1216 1336 1520 864 865 868 895 -hsync +vsync (53.7 kHz d) (II) modeset(G0): Modeline "1024x768"x120.1 133.47 1024 1100 1212 1400 768 768 770 794 doublescan -hsync +vsync (95.3 kHz d) (II) modeset(G0): Modeline "1024x768"x60.0 65.00 1024 1048 1184 1344 768 771 777 806 -hsync -vsync (48.4 kHz d) (II) modeset(G0): Modeline "960x720"x120.0 117.00 960 1024 1128 1300 720 720 722 750 doublescan -hsync +vsync (90.0 kHz d) (II) modeset(G0): Modeline "928x696"x120.1 109.15 928 976 1088 1264 696 696 698 719 doublescan -hsync +vsync (86.4 kHz d) (II) modeset(G0): Modeline "896x672"x120.0 102.40 896 960 1060 1224 672 672 674 697 doublescan -hsync +vsync (83.7 kHz d) (II) modeset(G0): Modeline "960x600"x120.0 77.00 960 984 1000 1040 600 601 604 617 doublescan +hsync -vsync (74.0 kHz d) (II) modeset(G0): Modeline "960x540"x120.0 69.25 960 984 1000 1040 540 541 544 555 doublescan +hsync -vsync (66.6 kHz d) (II) modeset(G0): Modeline "800x600"x120.0 81.00 800 832 928 1080 600 600 602 625 doublescan +hsync +vsync (75.0 kHz d) (II) modeset(G0): Modeline "800x600"x60.3 40.00 800 840 968 1056 600 601 605 628 +hsync +vsync (37.9 kHz d) (II) modeset(G0): Modeline "800x600"x56.2 36.00 800 824 896 1024 600 601 603 625 +hsync +vsync (35.2 kHz d) (II) modeset(G0): Modeline "840x525"x120.0 73.12 840 892 980 1120 525 526 529 544 doublescan -hsync +vsync (65.3 kHz d) (II) modeset(G0): Modeline "840x525"x119.8 59.50 840 864 880 920 525 526 529 540 doublescan +hsync -vsync (64.7 kHz d) (II) modeset(G0): Modeline "800x512"x120.3 51.56 800 800 828 832 512 512 514 515 doublescan +hsync +vsync (62.0 kHz d) (II) modeset(G0): Modeline "700x525"x120.0 61.00 700 744 820 940 525 526 532 541 doublescan +hsync +vsync (64.9 kHz d) (II) modeset(G0): Modeline "640x512"x120.0 54.00 640 664 720 844 512 512 514 533 doublescan +hsync +vsync (64.0 kHz d) (II) modeset(G0): Modeline "720x450"x119.8 53.25 720 760 836 952 450 451 454 467 doublescan -hsync +vsync (55.9 kHz d) (II) modeset(G0): Modeline "640x480"x120.0 54.00 640 688 744 900 480 480 482 500 doublescan +hsync +vsync (60.0 kHz d) (II) modeset(G0): Modeline "640x480"x59.9 25.18 640 656 752 800 480 490 492 525 -hsync -vsync (31.5 kHz d) (II) modeset(G0): Modeline "680x384"x119.6 42.38 680 716 784 888 384 385 390 399 doublescan -hsync +vsync (47.7 kHz d) (II) modeset(G0): Modeline "680x384"x119.9 36.00 680 704 720 760 384 385 390 395 doublescan +hsync -vsync (47.4 kHz d) (II) modeset(G0): Modeline "576x432"x120.1 40.81 576 608 668 760 432 432 434 447 doublescan -hsync +vsync (53.7 kHz d) (II) modeset(G0): Modeline "512x384"x120.0 32.50 512 524 592 672 384 385 388 403 doublescan -hsync -vsync (48.4 kHz d) (II) modeset(G0): Modeline "400x300"x120.6 20.00 400 420 484 528 300 300 302 314 doublescan +hsync +vsync (37.9 kHz d) (II) modeset(G0): Modeline "400x300"x112.7 18.00 400 412 448 512 300 300 301 312 doublescan +hsync +vsync (35.2 kHz d) (II) modeset(G0): Modeline "320x240"x120.1 12.59 320 328 376 400 240 245 246 262 doublescan -hsync -vsync (31.5 kHz d) (II) modeset(G0): EDID for output HDMI-1-1 (==) modeset(G0): Using gamma correction (1.0, 1.0, 1.0) (==) modeset(G0): DPI set to (96, 96) (II) Loading sub module "fb" (II) LoadModule: "fb" (II) Loading /usr/lib/xorg/modules/libfb.so (II) Module fb: vendor="X.Org Foundation" compiled for 1.19.3, module version = 1.0.0 ABI class: X.Org ANSI C Emulation, version 0.4 (II) Loading sub module "shadow" (II) LoadModule: "shadow" (II) Loading /usr/lib/xorg/modules/libshadow.so (II) Module shadow: vendor="X.Org Foundation" compiled for 1.19.3, module version = 1.1.0 ABI class: X.Org ANSI C Emulation, version 0.4 (--) Depth 24 pixmap format is 32 bpp (==) modeset(G0): Backing store enabled (==) modeset(G0): Silken mouse enabled (II) modeset(G0): RandR 1.2 enabled, ignore the following RandR disabled message. (==) modeset(G0): DPMS enabled (WW) modeset(G0): Option "AllowEmptyInitialConfiguration" is not used (WW) modeset(G0): Option "IgnoreDisplayDevices" is not used

While the first login falls back on glamourgl, which I think is the issue:

(II) config/udev: Adding drm device (/dev/dri/card0) (II) xfree86: Adding drm device (/dev/dri/card0) (II) LoadModule: "modesetting" (II) Loading /usr/lib/xorg/modules/drivers/modesetting_drv.so (II) Module modesetting: vendor="X.Org Foundation" compiled for 1.19.3, module version = 1.19.3 Module class: X.Org Video Driver ABI class: X.Org Video Driver, version 23.0 (II) UnloadModule: "modesetting" (II) Unloading modesetting (II) Failed to load module "modesetting" (already loaded, 22019) (II) modeset(G0): using drv /dev/dri/card0 (==) modeset(G0): Depth 24, (==) framebuffer bpp 32 (==) modeset(G0): RGB weight 888 (==) modeset(G0): Default visual is TrueColor (II) Loading sub module "glamoregl" (II) LoadModule: "glamoregl" (II) Loading /usr/lib/xorg/modules/libglamoregl.so (II) Module glamoregl: vendor="X.Org Foundation" compiled for 1.19.3, module version = 1.0.0 ABI class: X.Org ANSI C Emulation, version 0.4 (II) glamor: OpenGL accelerated X.org driver based. (EE) modeset(G0): eglGetDisplay() failed (EE) modeset(G0): glamor initialization failed (II) modeset(G0): ShadowFB: preferred YES, enabled YES (II) modeset(G0): Double-buffered shadow updates: off (II) modeset(G0): Output eDP-1-1 has no monitor section (II) modeset(G0): Output HDMI-1-1 has no monitor section (==) modeset(G0): Using gamma correction (1.0, 1.0, 1.0) (==) modeset(G0): DPI set to (96, 96) (II) Loading sub module "fb" (II) LoadModule: "fb" (II) Loading /usr/lib/xorg/modules/libfb.so (II) Module fb: vendor="X.Org Foundation" compiled for 1.19.3, module version = 1.0.0 ABI class: X.Org ANSI C Emulation, version 0.4 (II) Loading sub module "shadow" (II) LoadModule: "shadow" (II) Loading /usr/lib/xorg/modules/libshadow.so (II) Module shadow: vendor="X.Org Foundation" compiled for 1.19.3, module version = 1.1.0 ABI class: X.Org ANSI C Emulation, version 0.4 (==) modeset(G0): Backing store enabled (==) modeset(G0): Silken mouse enabled (II) modeset(G0): RandR 1.2 enabled, ignore the following RandR disabled message. (==) modeset(G0): DPMS enabled (WW) modeset(G0): Option "AllowEmptyInitialConfiguration" is not used (WW) modeset(G0): Option "IgnoreDisplayDevices" is not used (II) modeset(G0): Damage tracking initialized xf86: found device 2

Anyways any help solving this issue would be appreciated, and I am willing to test any possible fixes.