The files https://github.com/Octo-Studios/reliquified_ars_nouveau/blob/second-patch/src/main/resources/data/rarcompat/tags/item/mimic_loot.json and https://github.com/Octo-Studios/reliquified_ars_nouveau/blob/second-patch/src/main/resources/data/rarcompat/tags/item/mimificable.json contain invalid entries ("reliquified_ars_nouveau:emblem_of_devotion,")

Thanks for the information, we'll fix it soon!

hi. A fix has been released.
https://www.curseforge.com/minecraft/mc-mods/reliquified-ars-nouveau/files/6429133