That mod didn't cause crashes.. Here I tried to do the same thing without TLSkinCape. This time the game didn't crash while I was loading into twilight forest (often it crashes at this stage). I spend 2 minutes flying in one direction and minecraft crashed.
I tried to run the game with just twilight forest mod, and everything was ok. The game crashes only when I add Prehistoric Fauna.
crash-2021-10-30_16.40.33-server.txt

I have the same problem, only with those two mods together it happens to me.

I will need your crash report, as well as more information on what was happening when the game crashed.

Minecraft crashes while twilight forest is loading after entering portal. Sometimes It doesn't crash, but after I walk a little bit in the twilight forest it crashes.
crash-2021-10-26_17.34.33-server.txt

Probably from skincape mod. There is no mention of this mod there.

Having the same issue here. Here's my crashlog, looks like it is different than the OP's it mentions spawning your structures the twilight. Which could explain why it happens after loading a few chunks and not right away every time.
crash-2021-11-03_20.01.23-server.txt

Fixed for 2.1.2