I found a crash scenario that I suspect involves this mod and Botania, and potentially other mods that add persistent potion effects through equipped items. Playing Valhelsia 3.

1. Equip a Ring of the Mantle and a source of mana
2. Open inventory and click the Haste II effect
3. Game crashes with an error reporting "Unidentified Potion Effect"

Can you send me a crash report?

Sure, happy to send it
crash-2021-12-23_15.15.44-client.txt

Meh, can you please fix this by now? It is prevalently still an issue, because simply summoning a potion with /give @a and custom amplifiers above vanilla (eg 9) crash the game, and it shouldn't. You should have a default screen that displays when an error is thrown or a potion is otherwise unidentifiable via source.