mending bug

If you have mending on one or more armor, you need to remove them to repair other things effectively. Even, though your armor is fully repaired. I don't know whether it's WAI or a bug.

I have tested this issue in Windows 10 (both PC and VR versions), also in the Android Pocket Edition version and I am having the same issue.  Here are my specifics in the hopes it will help resolve this issue...

I first had Mending enchanted Fishing Rod and Bow, mending worked just fine on both of those, even when wearing full armor.  Fishing experience would repair the bow all the time.  It wasn't until I enchanted a Diamond Pickaxe that the mending stopped working for the Bow and the Pickaxe (mending for the fishing rod seems to be working still since my fishing rod never shows wear and tear).  I've tried removing the pickaxe from my inventory to see if experience received while fishing would go toward the bow again, but it goes to my leveling instead.  It does seem that experience received while mining will go toward the pickaxe as long as I do not have either the enchanted fishing rod nor the enchanted bow.  But I am not sure since it is hard to get enough experience mining to offset the wear and tear of the pickaxe.

Please, whatever the issue with this enchantment is, fix it.  The way it should work is, any experience gathered should go toward any item imbued with the Mending enchantment.  If that item is fully repaired, move on to the next item... so on and so forth until all items imbued with the enchantment that are either worn or on the quickslots are fully repaired, only then the experience should go to leveling.  

Thank you for your report!
However, this issue has been closed as Working as Intended.

More information can be read on the Wiki page

If you need help or have a suggestion you might like to follow a link below.

Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Feedback – 📖 Game Wiki

I think it should be reopened. It is exactly the same issue as MC-92889, which is fixed for java in 20w06a, so it can be reopened and the vanilla-parity label should also be added.

The way that mending currently works on bedrock and used to work on java before 20w06a is that whenever you pick up an experience orb the game choses a random item with mending that is in your hand or on an armor slot and when the item hasn’t full durability the item gets repaired, but if it has full durability the xp will instead go into the experience bar. What they have changed on java is that the game now only choses items that can be repaired when picking up experience, which means that every item that is in your hand or on an armor slot with mending needs to have full durability to make the xp go into the experience bar.

I have reported the same issue MCPE-80156 and it is confirmed. The parity rules changed so as far as i know, its 100% a valid bug.