Kind of an obscure mod but this datapack seems to cause a freeze in the nether with this mod, a temporary fix seems to be just removing the nether variants from the datapack

I got the world deadlock issue to happen and I did a thread dump to see what line of code the world is stuck on. It seems NetherPyrowoodRootsStructure is not worldgen safe and will deadlock the server. I'll try contacting them so they can fix their feature
https://paste.ee/p/MS4Cy

wait a second, this is an mcreator mod. Welp, that explains why it is broken lol. I'll still contact them but this report will be closed as with mcreator mods, mod compat is super sketchy and they generally have a ton of bugs