I was just thinking that. What can go wrong is when a backup fails.
The tool I am building speeds it up by saving the file list from the last run but even there, it needs ro handle restarting a failed run leaving the state in disarray (though theoretically without information lost). The approach I take is that if a run fails, it does list the destination again (a la regular rclone sync) to ensure the proper state.
That could break the ability to fully recover.
However, if a full snapshot recovery is of interest, this is not the tool. Restic, kopia, etc are the right approaches.