Requires Fabric - A Forge version is not planned.

FairEnchanting

In vanilla Minecraft, the cost to enchant tools/armor is always a set number of levels, no matter what your current level is. For example, if you're level 50, and enchant a sword with a level 30 / cost 3 enchantment, you're level 47, even though getting from 47 to 50 is nearly three times more experience than getting from 27 to 30! This mod does one thing: sets the cost of enchantments to be the amount of levels as if you were the minimum level required for the enchantment.

As of v1.1.0, now includes support for the Anvil - The cost is as if you were the required level!

Example: Player is level 30, selects the min 30 / cost 3 enchantment, is now level 27.

Example: Player is level 50, select a min 7 / cost 2 enchantment, is now level 49 (and some change)