Datapack not working after removing custom enchantment

I had added custom enchantments to my datapack. After testing I found a more convenient way to implement the same behavior and deleted the enchantments and every trace of them (at least that's what I hope I did).
Now when I wanted to test the new way I got the following error and don't really understand it:
EDIT: Also tested it on a new world and it said "datapack validation failed"