I was playing on Survival trying to survive starting in the Nether, in Pre-release 8. I was attacked by a Piglin with low hunger so health was not regenerating. Each hit from the Piglin's sword was doing 4 hearts of damage exactly, whereas before it was doing 4.5 hearts.

I switched to Hard Mode to test this out further, and where Piglins previously did 6.5 hears of damage per hit, they now did 6.

It's not been mentioned in any changelog which makes me think it is a bug rather than a silent Piglin nerf.