Spawners, created through applying spawn eggs to the spawner block obtained through commands, for Enderman and Zombified Piglin mobs create exceptions loading entity every tick.
Classed in the output log under 'warn'.
Exception loading entity:
u: Loading entity NBT
at aqe$$Lambda$4235/2041367260.accept(Unknown Source)
at ecd$$Lambda$4676/396463835.run(Unknown Source)
Caused by: java.lang.ClassCastException: dwt cannot be cast to aag
at baa.a(SourceFile:260) at aqa.f(SourceFile:1654)
... 20 more