I have again found groups I never added to my profile!

I find that is true on mine from time to time too.
Groups added, occasionally messages read.

I don't know who or what does it, but its not uncommon from what I've gathered.

I suspect they sometimes rename groups.

This website has a lot of bugs

It happens randomly, its crap

I've found this too.

I don't know if SW compares your Forum lists with those of people to whom you respond, finds vague matches by pure word co-incidence, and so adds them to your own.

However it actually is creating these unsolicited background additions, it needs stopping.

😳