hectorrajado

This issue was incorrectly marked as resolved in MC-276610. I'm unaware of what the correct procedure is in this case, but since it affects a new version I created a new bug report for it, including the information from the comments of the previous report. If the bug report is meant to remain in one place, I hope a mod can come and mark this as a duplicate, and reopen MC-276610. Otherwise I hope this is resolved here.

I've proceeded to do some more tests, and I've gained some new insight. It seems like ender pearls are in fact interacting as they should, but some bug is forcing them down more than before. I've attached some new images showcasing what I found. It seems as though all ender pearls get forced two blocks below where they previously would have stopped.

As seen in both the 4 block tall bubble column, and the 5 block tall bubble column, ender pearls now seem to stop consistently 3 blocks below where it was thrown (2 blocks below where they would originally in 1.21.1). This explains why the original functionality no longer works in the original design, as the pearls would have tried to stop below ground.

Considering the difference between versions is 2 blocks, I suspect this may have something to with some change in the snapshot now making calculations with reference to the player's feet, instead of with reference to the player's head as it did previously (although this is merely speculation)

I'll await confirmation as to whether this is an intentional change, which would be very disappointing.

No, it's a separate issue

Yes, I'm certain 100%. I first encountered the issue in another superflat world I made which was in peaceful mode, where I had a bunch of frogs trapped inside a size 50 world border. Since it was in peaceful mode and the worldborder was so small, no slimes spawned, but all the frogs ended up at the south east corner anyway. That's when I decided to re-create the issue in this second superflat world where I observed the same behaviour, all the frogs ended up at the south east corner specifically.

Note that I did find some new information. This behaviour seems to only appear in terrain that is completely flat without any plants or blocks. Once I bonemealed the grass and there were plants and flowers everywhere, the frogs seemed to spread uniformly like they should. I didn't test this in any other kind of terrain though, only flat with nothing and flat with plants.

I assume that what's happening is that when frogs have nothing to jump on, they jump "randomly" which has a tendency to take them south east. However, when the area is full of plants, the frogs prioritize jumping on the plants, and since the plants are everywhere, the frogs spread everywhere. I noticed this too when I placed a single block in the middle of the area, the frogs would prioritize jumping on the block as opposed to jumping on the flat floor, and so a small group of frogs would remain clumped around the block while the others spread like in the pictures above.

So I guess the way to fix this issue would be to tweak the "randomness" of where frogs will jump if they have nothing else to jump on, since right now it seems to have a tendency to take them south east. But that's just my best guess.