@adam-broda I was looking for a solution to this irritation when I found a post from 2 years ago mentioning the same issue: Whatsapp and Facebook messenger keep activating themselves.
It's an issue that they seem to ignore, so they're definitely forcing these "features" on us. I had Instagram active previously and didn't have this happening to me, it's only since removing it that the messenger feature keeps bugging me. So, if you don't want to switch to a different browser, perhaps try activating at least one and see if that works? I'm going to try this myself and see what happens. I don't feel like going back to Chrome just yet.