Witches that naturally spawn and join raids don't despawn, stalling raid progress until that witch is killed

When a witch spawns somewhere near a village (usually underground in a hidden area) during a raid, it won't despawn even though it should because it spawned naturally. This causes raids in villages to stay forever until you mine out the entire area near the village to look for the witch and kill it.

To reproduce, spawn a witch in a safe place during a raid and it won't despawn when you wait, or move at least 128 blocks away.