Pruning judgement. Leave stub? Is it grafted now?
This is what weak "V" unions between codominant trunks can lead too.
Not rare, but not common. Fasciated twig on Flowering Cherry. Can be pruned off.
Dark area between is another example of included bark. A weak zone.
This is what happens when pruning is not done and when trunks are too close.
Small bladder mites cause this leaf reaction. No big deal. In a way, its interesting.