FSE is down and it is still happening: ping times to the gateway are worse than ping times to Cockbox right now. It is a flood. When FSE is back up, it will still be a flood but it will be hosing my DB. The problem is on the other side. If you are delivering every activity 150 times, it's hosed already.
Returning 200 isn't a fix: it just makes it get delivered 150 times instead of 450 or 750 or whatever the retry threshold is. A fix would be delivering once.
Someone clicks Like once, and that's one request that triggers a delivery to N servers, right? Unavoidable. But now it's one request triggering one request per follower. That is a catastrophe. That is an accidental DDoS already.