The bug

It's featured that some mobs can spread their anger to other mobs between individuals and even species. However, they are able to spread the anger to any mob, including the anger to other individuals in their species. Thus, although it's unable to normally make the mob angry with itself(e.g. by throwing snowballs), it's possible to make another individual angry with the former mob, and simply let the latter mob spread its anger to the formal mob, causing the former mob to be angry with itself. As the former mob becomes angry with itself, it will abnormally attack itself, eventually killing itself, which is a weird behavior.

In detail, zombies can spread angers to other zombies, husks, zombie villagers and drowned. Pillagers, blazes, husks, zombie villagers, zombified piglins and drowned only spread anger to their corresponding species. Piglins and piglin brutes spread angers between two species.

Videos are provided.