Hi,
Long story short, NEA and TRLib don't work together. The last time they worked together was on the 23rd of October 2022 (today I decided to play and here we are...)
Forge version: 1.16.5 - 36.2.39

1.16 is not supported anymore exactly because of the lib. Looks like some forge load order issue. Try just loading the lib and see if it shows up/different forge versions.

Works both alone and with NEA
Must be a compatibility issue with one of the mods I updated from the modpack I used.

These are the mods that were updated (Geckolib was removed. It didn't work with and without it (I didn't need it anymore))

Closing this as the 1.16 version is about to be replaced.