I noticed a fail with the xp distribution if you have armor(fully repaired) with mending. If you have no armor with mending the xp you pick up will repair tools or armor with mending in your main hand and in the of hand, and none of that xp you pick up will get collected in the players xp bar. But if you have mending on your armor fully repaired the tool or armor in your main or of hand xp you pick up will try to repair the armor and the items in your main hand and in of hand and if it tries repair the armor(fully repaired) the xp will collect in your players xp bar.

In my mind it feels like that should not be the case, so for the fix you might want to remove that the game tries to choose armor fully repaired and not give you xp in your bar when you have armor with mending(fully repaired) and a tool or armor in your of hand and main hand then it should only be able to try choose the damages tools/armor.