Replies from 1 April 2022

It definitely is for "real" users, so I'd assume that it'd be the same for the GitLab-generated service accounts, too

Maybe if you can set up a wildcard Gravatar for your no reply domain?

Sometimes it's based on an app that will look at who you're following and block accordingly ie if you're following a known transphobe, supporter of brexit, convicted sex assaulted etc. Definitely false positives at times (likely like yourself!) but does protect folks from being interacted with people they don't want too