Mending doesn't affect Warped Funguses On A Stick when in the hotbar. The only way to repair it with experience is when it is in the offhand
MC-176191
Warped fungus on a stick is only affected by mending if it is in the offhand slot.
Resolved
Cannot Reproduce
0
Cannot reproduce, you can mend your fungus on a stick in the main hand too.
Note that mending does only work to the items you're wearing or holding, but that applies to mending in general.