Inconsistent movement behaviour

I will present two different parkour scenarios, in which seemingly better initial conditions lead to worse outcomes, causing what I believe to be inconsistent and very unpleasurable movement behaviour. All versions 1.21+ are affected, most likely related to MC-275671. I have provided setups that are hopefully easy to replicate.

Jump 1: (Setup in jump1.png and two attemps in jump1_success.mp4 and jump1_fail.mp4)

In the successful attempt you can see me walking up all the way to the wall and then simultaneously jumping and starting to run towards the jump while holding space. In the failed attempt, I moved forward by around 0.25 blocks and repeated the exact same timing as before. Even though logic dictates that we should be able to make the jump, this is in fact not the case.

Jump 2: (Setup in jump2.png and two attempts in jump2_success.mp4 and jump2_fail.mp4)

Running over a one block gap is a very infamous and intended mechanic and when using the setup in jump2.png with a full block instead of a block of farmland everything works as intended. However, if we try the same thing with a block of farmland (which is one pixel shorter than a full block), we will always fail the jump, even though it should clearly be easier in theory.