NOTE, this was tested on realms. Player knockback is broken after the latest update (not 100% sure if this bug is in mc preview). Basically when another player hits you u normally take abit of knockback but now you go absolutely flying (not literally). The bug is amplified when the player punching the other player is moving. NOTE, this was tested with multiple items in the players hand including just the fist and the results were still the same
Linked issues
is duplicated by 8
BDS-22776
Server auth movement issues
Resolved
MCPE-191426
"Problem 1 Knockback increase(it has excelled to a greater amount so it's harder to do things such as combo)
Resolved
MCPE-191452
"Problem 1 Knockback increase
Resolved
MCPE-218114
Mobs deal excessive knockback compared to normal in Bedrock Preview 1.21.90.21 (PS5)
Resolved
MCPE-218270
Hitting mobs/players
Resolved
3 more links
This is related to the server authoritative movement changes from 1.21.60. Reverting the pointless server auth movement change (that also causes many other issues) will fix this bug.