2025091000 didn't fix things for me as well.
I'm one of the people where RCS said connected, but everything started falling back to SMS three days. I tried yesterday deleting cache and data and rebooting the phone, which didn't fix things, but did make Messages switch to saying "setting up" "trying to verify your number." Once I got 20205091000 and rebooted it didn't help. Then I tried deleting data and cache and rebooting again, but that didn't help either. Maybe I should have left things alone yesterday and it would be working now? Sigh.
Does leaving RCS on and stuck at "trying to verify your phone number" risk using up a lot of battery life?
The most frustrating part, as others have said, is how this breaks RCS group chats and doesn't just fall back to MMS. All of my supposed RCS group chats originally were SMS, but then just got automatically converted to RCS, once everyone was on RCS. Now I have to create new groups, which I'm sure is only going to confuse people. Honestly, this speaks to how RCS is not a viable replacement. If it can't fall back to MMS, then it's more reliable not to use RCS, so that group chats can't get broken in this way.
That being said, I did like having RCS working. This is the first thing, in more than two years, that has made me feel like maybe GrapheneOS isn't worth it. I don't want to have to spend tons of time troubleshooting basic phone functionality. I kind of feel beaten into submission and like I should just submit to the Google overlords.