crash-2021-08-26_14.11.17-server.txt
Crash report uploaded.
Occurred when updating and loading into a test world that was working in previous version. it also coincided with this crash on client side at the exact same time.
crash-2021-08-26_14.11.24-client.txt

After a quick test, backdating to 1.21.5 lets the world load normally. So, I'll wait... :V

Please try this version: https://www.curseforge.com/minecraft/mc-mods/ars-nouveau/files/3439724

oh shoot. I didn't come back and say that it worked. X_x I completely spaced on that when you uploaded the new one... :V