Downloaded the newest version released for forge 1.16.5 and the game crashed
https://paste.ubuntu.com/p/bnczZcbTt4/

Huh, the class name of GeoModelException was apparently changed to GeckoLibException on version 3.0.15; a temporary fix would be to use version 3.0.14 until mods switch to the new name.
You may want to notify relevant mod authors about the name change (the author of arsnouveau in this case) if they're not already aware.

Correct, this would be an issue with ars with was fixed with baileyholl/Ars-Nouveau@649e97f