I've just seen this too – the crash was an "out of memory" and then the game showed some super weird behaviour. Unfortunately I didn't think to get the frame grapher up before it crashed, but I did record some of what happened after the crash.
Wasn't a single biome world
Was in a forest, not in plains
Unfortunately was afk when the framerate first died
The world didn't save and I haven't been able to reproduce the issue.
Machine:
Linux 21.04
Intel 10105F processor
GTX 1650 GPU
Ty bugsbugsbugs, that is indeed the same issue.
What it looks like: https://www.youtube.com/watch?v=qbe0TPF_Ve0