Question Regarding Google Android Backup Encryption

I would treat it as not protected by the screen-lock layer unless Google says that exact RCS media type is included. Their wording carves out Photos/Google Photos and carrier MMS media, but it does not clearly say “RCS attachments are client-side encrypted with your lock screen.” For a conservative setup, I’d avoid relying on Android cloud backup for sensitive message media and keep important files in an app/service where the backup encryption model is explicit.