I've noticed that the skeletons from my mob spawner farm do not drop bows or armor since updating to 1.21.4. Other mobs seem to drop loot at the usual rates and skeletons spawning not from spawners seem to as well.

Another player on the realm also tried and didn't have anything except bones and arrows drop either.

I have an older save backup from before I edited a small part of the world after the 1.21.4 update to reset an area that would be pale garden in 1.21.4 but we had already explored, and checked this in singleplayer and had the same issues even in the unedited backup file.