As we start to see more users join, it’s inevitable to see trolls (especially low-effort trolls) making more of an appearance and trying to be controversial and noticed.
Best just to scroll past them. They want to spark unwinnable arguments and rack up negative rep. If something seems absurdly ridiculous or inciteful, just move on. It’s not even worth down voting.
Did you turn them off (or maybe you never turned them on, I don’t recall what was default state)? They’re working for me from what I can tell.
Settings -> Notifications
I’m not the person you asked, but no. It’s a bug. I experience the same. I only get reply notifications if somebody uses @.