The bug
Monster spawner tries to spawn breezes when the difficulty is Peaceful.
Steps to reproduce
Set the game difficulty level to Peaceful.
/difficulty peaceful
Set the game time to night.
/time set night
Summon a monster spawner with breeze.
/setblock ~ ~ ~ spawner{SpawnData:{entity:{id:breeze}},Delay:1} replace
Notice that the breeze disappears immediately after being spawned.
Can confirm 1.20.3-pre2