When you fight an enemy that is a more than two levels above you in Borderlands 2, you inflict less damage than usual:

This chart shows how much damage you lose. For example when shooting an enemy that is 6 levels higher than you, if you normally do 1000 damage, you will instead inflict 670 damage, and when shooting an enemy 19 levels above you, you will only do 50 damage.

20 levels or more higher than player: 99% damage reduction

19 levels higher than player: 95%

18 levels higher than player: 90%

17 levels higher than player: 87.6%

16 levels higher than player: 84.2%

15 levels higher than player: 81%

14 levels higher than player: 76.9%

13 levels higher than player: 74.5%

12 levels higher than player: 73.8%

11 levels higher than player: 70%

10 levels higher than player: 64.1%

9 levels higher than player: 59.2%

8 levels higher than player: 53.6%

7 levels higher than player: 48.6%

6 levels higher than player: 44.0%

5 levels higher than player: 30.9%

4 levels higher than player: 28.2%

3 levels higher than player: 17.1% damage reduction

0-2 levels higher than player: No Damage Loss.