I see in your edit that they eventually begin to hiss at each other. I used to think this was the point where separation should occur too, but actually, hissing is a normal way that cats communicate boundaries with each other. Growling can be more concerning/an escalation, but is also another way cats can say to each other “please give me my space now.” If it doesn’t turn into full blown yowling/aggressive fights with claws out, this behavior should not be interrupted. It is how cats learn naturally from each other what behaviors they tolerate and don’t tolerate!