Google Backup & Sync makes it very cumbersome to retain a local copy of your photos. They used to sync them to Google Drive, so you could at least use Backup & Sync to have local copies. However, they got rid of that feature some time in the last year.
I had to switch to using a third party app to sync my "photo reel" from my phone to Google Drive: https://play.google.com/store/apps/details?id=com.ttxapps.dr...
Then I use Google Backup & Sync to create a local copy on my desktop, scheduled SyncToy job to copy it to the NAS, and the NAS has a scheduled job to backup to Backblaze B2. In my setup, these irreplaceable photos & videos exist on my phone, Google, my desktop, my NAS, and Backblaze.
If you are relying on Google Backup & Sync to restore a large amount of data after a data loss event, you are in for a world of pain and disappointment. It simply does not handle any significant amount of data well. I had to stop backing up "My Computer" with Backup & Sync and just switched to using Google Drive. The files in Google Drive seem to be the only way to "restore" a large amount of files after a data loss event. If they are backed up under "My Computer" in Google Drive and you have a decent amount of data (50GB+), you will have no way to restore these files. The web interface will simply time out when you try to download them. The Backup & Sync client won't even attempt to download these files, even if you try the dead-end workarounds suggested on the web. You won't be able to drag them into your "Google Drive" folder as a workaround either. The whole thing is atrocious.
Google Backup & Sync is a fucking joke, and Google should be ashamed of themselves for releasing such a shitty product which does not actually help consumers protect against data loss. Consumers will only realize this at the point they are fucked and trying to restore their data.