Just activated the Pixel 5, but I’m having issues where RCS on Google Messages is picking up my underlying RW number rather than using my actual phone number. This was working perfectly on my old phone, and I’m not quite sure how to resolve this issue. In the meantime I have disabled the chat features so that I can continue to use my phone with SMS. Yes, I am aware the RW does not officially support RCS.
It only works if your phone has a GSM SIM. If the phone has a CDMA SIM the underlying number shows and there is no solution to this issue at this time.
FWIW, I briefly had the same issue with my new phone. Switching to SMS and then back to RCS quickly and permanently fixed the issue for me. Probably worth a shot.