I argue that it clearly is. Per the wiki "A player holding sneak does not bounce at all and takes fall damage," which does not align with what I demonstrated.
Player movement is calculated serverside (an officially hosted realm in this case) so reproducing with a vanilla client should not be necessary. Either way I have now attached a demo on vanilla 1.17. Took me three attempts to reproduce if that is interesting.
It does not. Breaking your fall is an indended mechanic, as is holding jump to minimize the bounce. Breaking your fall and still bouncing is not intended.
This behavior also makes it possible to place lily pads on top of a block by clicking on the side or bottom of said block. I have uploaded a few screenshots of this.