> If they're deployed separately, they don't share the release cycle. Sooner or later you'll end up with mismatched versions of them running (e.g. perhaps one piece fails to deploy). So you need to be prepared for that, so you want them in separate repos so you can easily test with different versions.

In that case I'll just rollback the first one. I see no reason to logically decouple two processes into two services when the separation is technically driven. They share the queues, the database, the domain, further division will just make things more complex with no obvious advantage.