Thank you jeanchen, I now unfollowed both communities, let's see what happens.
However, I did not make a change to what I follow when the undesired notifications started to come to me. I always had it set so that threads I participated in would notify me.
It was my understanding that following a community would put news regarding it on some sort of main page in the Communities site, perhaps I misunderstood the purpose but I certainly never got notifications for either of those two in the past.
Thanks for your help!
Mathias