It was reported in late November that Google Drive for desktop (v184.108.40.206-220.127.116.11) had a sync issue, which caused months or even years of files to disappear. If you were unfortunate enough to be part of this "small subset" of users, there's finally some good news. In the latest version of Drive for desktop app (version 18.104.22.168 or higher), you'll be able to access a file recovery tool via a few steps: go to the menu bar or system tray, click the Drive for desktop icon, press and hold the "Shift" key and click "Settings," and then you'll be able to hit "Recover from backups."
From there, you should see a notification saying "Recovery has started," and hopefully you'll get a "Recovery is complete" message after a while. You'll then find a new folder named "Google Drive Recovery" containing the unsynced files on your desktop.
Good luck, though, as Google doesn't expect this method to work for everyone. "If you’ve tried to run the recovery tool and are experiencing issues, submit feedback through the Drive for desktop app with the hashtag '#DFD84' and make sure to check the box to include diagnostic logs," the company said on the support page. There are also instructions for those who prefer trying with command line interface, Windows backup and Time Machine backup.