There was also a support topic on this upgrade https://doc.e.foundation/support-topics/s7-upgrade-to-r-guide.html.
On the basis that we are talking about the stable releases (found on any device bought from Murena) … there would be risk of loss of data, but in the case that a “new” Android 11 (R) build has failed to be initiated you may be able to sideload an earlier Android 10 (Q) ROM so that you are able to take the correct stable Upgrade path via v1.17.1-q.
Worth searching for forum posts February / March time where SAMSUNG S7 SM-G930F users had some success “going back” where the OTA upgrade got tripped up by missing the “v1.17.1-q warning”, here’s one Stuck at "finalizing the system update".