After about an hour of trial and error, I pinned the issue to mob heads. This issue only happens on 1.21.9 and 1.21.10 and has not happened for any other version for me. The crash happens whenever I look at any placed mob head. This includes either looking at it directly or around the area it was placed. To explain more about the second cause, let's say I had the mod off and I proceeded to place a mob head on one of the walls in my house. Then went outside to the opposite side of that wall but I'm not currently looking at it. If I were to reenable the mod and looked at that wall, even for a split second, it crashes. Then the world continues to crash until I disable to mod. It can't be any of the other mods I have installed since this mod has worked perfectly fine with them for the past year on many different versions (I use CurseForge).

If you need any more details about anything I will happily provide them.

Edit 1: Just tested something else out. I proceeded to remove all the mods besides this one and it still crashed when looking at mob heads.
Edit 2: Went on older versions to fact check and they worked with no issues or crashing. Only 1.21.9 and 1.21.10 has this issue.

Duplicate #270