For some reason I've been getting this. I've looked at other topics about this but they tend to have been made for 1.16.1 and I've still got no clue on to what constitutes as a broken datapack.
This is what should hopefully be the log and the debug assuming I haven't done anything wrong.
Appears it was Alex's mobs, and I need to learn to look at the last things that happened. If I need to take this down msg me, otherwise i'll elave it up for anyone who finds it helpful.