Witch Hut Bounding Box Can Spawn Other Mobs

Built a witch farm, yesterday, in 20w20b on my canilla survival server. In a single player world I checked the bounding box location several times. I built the farm perfectly around it. It was working fine with no problems yesterday, but today, other mobs are spawning inside of it. In fact I've seen almost no witches at all. Now I thought I might just be losing my marbles but in fact I was not. I just tested it in the world download of my server. In 20w20b the farm runs perfectly with no problems. Upon moving the world to 20w21a it is now spawning bunches of other hostile mobs. I didn't know what screenshots to include so I included images of the bounding box, it was checked with two different mods, both confirming the farm was in the correct area.