Pickaxe with Mending not repairing itself

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A crash did not occur.

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I apologise, I was in a hurry.

I have a number of tools with the Mending enchantment. I have a zombie XP farm. Until the last update (I think, I don't think I used the XP farm during the previous update) when I collected XP with my tool in my hand the tool's durability would increase. This is going very, very slowly at the moment. My XP bar increases at a normal speed but the tool repairing has slowed to a crawl.

Are you wearing any mending armor/gear? All xp is split between any worn items with mending, even if they have full durability. If xp is sent to armor that has full durability, you will gain experience instead of having your pick repaired. So wearing full mending armor will decrease your pick repair rate by 80%.

Okay, that explains it. Could I make the suggestion that that is maybe changed in the future. Thanks for your help.