I didn't see another post of this nature, I apologize if this has already been brought up.
Tamed cats teleport back to you when they get out of range. The rats will chase the tamed cat away, but it just teleports back and they get stuck in this loop of chasing the tamed cat, even when the cat is sitting.

Ideally, I would love the option to turn off the rats chasing cats behavior so that I can also have a pet cat along with my pet rats, but that's just a suggestion.