The imperishable enchant is only taking 1 level to apply in the 1.15.2 build. Is this a bug or did you change it to work like other enchants?

I have just tested this for a good bit and I can't reproduce. Closing for now, let me know if you find any other mods conflicting with enchantments and causing this issue! 😀

Oh like when you apply it to a tool in an anvil? Making sure it's not that it's able to get it via enchanting.