Retry storms are "easy" exponential backoff with jitter. Like what ethernet on shared media has been doing since the 80s.

If that's not enough to come back from an outage, you need to put in load shedding and/or back pressure. There's no sense accepting all the requests and then not servicing any in time.

You want to be able to accept and do work on requests that are likely to succeed within reasonable latency bounds, and drop the rest --- but being careful that an instant error may feed back into retry storms, sometimes it's better if such errors come after a delay, so that the client is stuck waiting (back pressure)