so i found out u can kill mobs that u summoned with gold experience and still get their loot, basically kill cow by using fire or absorp ability from pillarman
this bug also happens with other mods like guard villager mod, basically kill the guard with fire or absorp ability(pillarman power) and u get iron chest, gold leggings, etc.
this bug may be on par with https://discord.com/channels/912347321633755156/1369171096326246480 if u have mods that has mobs that drop op loot and that mob can be summoned with ge