Another form of argumentus interruptus is when the other suddenly weakens their claim, without acknowledging the weakening as a concession

I used to do this quite often. Usually in personal conversations rather than online, because I would get caught up in trying to win. I didn't really notice I was doing it until I heard someone grumbling about such behavior and realized I was among the guilty. Now I try to catch myself before retreating, and make sure to acknowledge the point.

So not much to add, other than the encouraging observation that people can occasionally improve their behavior by reading this sort of stuff.