I don't see any signs of mites on your budgie. He does appear have a little injury on his beak that was possibly caused by an attack from another bird or some kind of accident (maybe a crash landing resulting from bumping into a wall while flying, or a night fright).
The wound is almost completely healed, so at this point there is no reason for worries.
The wound is almost completely healed, so at this point there is no reason for worries.