in snapshot 20W06A knockback resistance was supposed to be changed from a probability to a scale and i believe that currently knockback resistance is both a scale and a probability, evidence? read below...

so to reproduce this bug first create a new, clean mc server, open 2 minecraft clients, join the server, give one player a regular netherite armor set and with the other player start hitting the netherite player and see the result

result?
the person wearing netherite armor will completely ignore knockback (imo this is unintended)
or get knockbacked just a little (intended effect)

what should happen?
person with netherite armor should always get knockbacked just a little

i've uploaded a short video demonstrating the bug
https://www.youtube.com/watch?v=QPx_1249DNk
yes i know... this was on a non-vanilla server but i've retested it on vanilla and the same happens