Level 30 Enchantments are nerfed across the board. Normal endgame enchantments almost impossible to get through enchanting.

When enchanting a level 30 enchantment, the outcome of said enchantment is much, much lower than it used to be, including also the ability to get level 1 enchants from a level 30 enchantment. This has not been here in previous version up to 1.13.2, but was introduced in 1.14.