The bug
If you use a Mace and perform a smashing attack, mobs nearby will get set into air. Since it was caused by the player, one would assume that the game would count it as a player kill. However, it does not. These mobs will not be counted in your statistics and they won't drop any XP either.
Reproduction steps:
Obtain a Mace
Set up a contraption like in the screenshot (the black concrete is unnecessary, it was used just to make it clear to see that these mobs I killed didn't drop any XP)
Spawn several mobs on top, make sure that the fall when you knock them off kills them
Go a few blocks up, enough to perform a smashing attack
Drop down and hit a mob
→❌ It is not counted as your kill. You can easily check it by looking down - there won't be any XP. And statistics will not count them either. Only the mob you hit counts as a player kill, if the attack is enough to kill it.
May be intended but I can confirm:
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