Ahh I see now. If you are talking about it not registering towards total damage done per match, it might be that the damage done his shield counts as damage done to other objects like Rampart's walls or Newcastle's shield/wall - as in not counting towards total damage done. Doesn't make sense to me, since hitting him = hitting a legend rather than a stationary wall with big hitbox, so probably a bug, not a big issue tho.

Regarding that 75 cap and 81 damage, damage done over his shield counts probably doesn't bleed onto him then, would be best to test with kraber in firing range, but that will probably be another bug, but now I can see why I have failed to kill ulting revenants in the past few days.

I might be wrong, but I think I remember reading in the patch notes that his shield takes less damage, kind of like headshots do less damage to enemies with helmets. Either way whenever this is a bug or intended case, revenant is a bit OP with his ultimate at the moment.