That's the problem with Google Drive or any synced state clouds. People think about them as "I have it on my local computer and in the cloud, so I'm much safer".

A lot of bad things can happen that are even invisible to the user until they find out data is missing.

You save a file on a disk, something goes wrong with the cloud client, especially on bad connection and your file is either never synced (you will lose it on OS reinstall) or even deleted on your side.

Cloud provider has some issues, they restore the backup and things are synced back on your computer to their restored state.

Cloud provider started to dislike a file (their antivirus marked it), so they remove it from their side and it syncs to your computer. But that was a false positive (well, you could have your reasons to keep the infected file as well).

Ok, I know, at least for Google Drive their official client is pretty well written (I was using it for a long time), but bugs happen.

Conclusion? Make your own backup.