I apologize if i cant provide enough information to be helpful, if you need more please do respond to tell me what i need to add to be of help.
I was fighting several mobs from different mobs, and as i was i encountered a freeze/crash type thing where everything in Minecraft just turned a solid buleish grey color, and pressing any button wouldnt work.
I posted the issue on the modded minecraft discord and they said that the issue was likely due to L2 Library. The only mod i had that was dependent on it at the time was modular golems.
edit:forgot to mention this is occurring in1.20.1

latest.log

Red Marker modifier checks mob effects on client side. However, mob effects are not synchronized to client for non-players. I use L2Library to sync certain mob effects to client for mobs to allow Red Marker modifier to work properly.

Twilight Construct updated. Reopen the issue if you get something else

Twilight Construct conflicts with some mods deleting capability on client. Will update Twilight Construct to prevent crash, but you might need to find out who is deleting my capability. Otherwise Red Marker modifier will never work