Under strange circumstances, I managed to get the following error, probably caused by using WATERMeDIA: Multimedia API.
I can't be sure, but I can say that this happens when using a link to a specific webp.

Game version: 1.21.1
NeoForge version: 21.1.211

The game crash itself: https://hastebin.com/share/esijejatul.yaml

And I attached the file.
hs_err_pid7208.log

P.S. I also noticed that the whitelist works for some non-OP players if the whitelist itself is enabled. I'm not sure why it works this way and I have no idea why this is the case.

And because its a super strange bug that might happens 1/1,000,000, i will close it. I am not happy to let it unfixed but I hope that it was fixed on the newer v3 update