Putting stuff in and out of an enchantment table fluctuates the level requirement

When I was done exploring and came back to my base to see what enchantments I could get when I get level 30 I saw the level req. cost on the bottom was 32 which shouldn't be possible.
Because I was curious when I took the lapis out it fluctuated and when a kept taking either the item I want to enchant out or the lapis the level req. fluctuated.

Haven't tested on any other versions.