The latest release of GrapheneOS is significant because it now has official support for using RCS in Google Messages. This is to try and address the ongoing RCS disconnect users on both stock and non-stock Android have been experiencing worldwide.
Some technical analysis of the disconnect can be found in later messages in this long-term RCS thread:
Looking through my spam box for the ones I had to manually report it looks like maybe close to one a week, and they tend to be very similar, usually wrapped around a popular pharmacy store chain (no attachments). I also have noticed they tend to be sent from gmail.com addresses, which may suggest why they're not getting trapped by the spam filter.
Some technical analysis of the disconnect can be found in later messages in this long-term RCS thread:
https://discuss.grapheneos.org/d/1353-using-rcs-with-google-...