This is very interesting. Why? Here's my fairly scientific take.



We think that the poor low-light performance on unrooted/unlocked phones is caused by the phone's image processing software.

Rooting removes some Sony proprietary imaging software eg X-reality.

The OP's images are much improved, suggesting that this third-party app is able to access unprocessed image data.



To test this it would be a real help if the OP could let us know if the images are also improved with the Sony camera app?