Steps to reproduce:
1: Obtain a sword with Fire Aspect II and Looting III.
2: Find an Enderman.
3: Kill said Enderman with the Fire Aspect, Looting sword.
4: The Enderman will drop 0-1 ender pearls instead of the normal 0-4 for Looting III.
This occurred on vanilla servers running 1.15.2, 1.16.1, and 1.16.2.
can´t confirm, maybe the endermen is kill by fire effect and don't apply as a kill by the player