So I have a 7x4x7 pond filled with source water blocks. This is a world I started more than a year ago and sometime in the past I placed two axolotls here. They were happily swimming around the pond, up and down, in every direction, making happy axolotl sounds.

In 24w35a I noticed strange "thumping" noises from the pond (like a mob stepping on the stone) and went to investigate. Axolotls were no longer swimming around the pond, they were like stuck to the bottom of the pond (swimming only along horizontal axis) and constantly trying to "break through" the bottom (top axolotl in the screenshot) which produced these "thumping" sounds.

Is it some kind of AI bug?