If you're observing deleted files, and you don't have any third party applications with access to your Drive, we'd be very interested in hearing from you, we take data integrity issues very seriously.
You can check the activity under any folder and see what issued the deletes. If there are missing files _without_ an entry there, and it doesn't seem to be a rogue integration with the Drive API, feel free to get in touch with me.
Despite my acidulous comment I have only once personally experienced a silent deletion, and it was with a Google Sheet a few years ago.
It was a "Copy of" produced by "make a copy" menu option that ended up deleted, which I confirmed with someone else who also had made a copy the same exact way, who couldnt access theirs either. Is this expected behavior when the source file is deleted, or is it, as I thought, a bug?
Without being able to look at the item in question, I couldn't tell. However, deleting copies when a source file disappears is unexpected and as far as I'm aware there's no mechanism for "dependent" deletes.
Where did you copy the item to? Was it stored in your My Drive?
Google Drive deletes files randomly (whether due to programmatic/storage problems or the documented issue with the algo not liking things and silently deleting them).
Missing block level sync reinforces that it's a toy. What would you do with 100+gb they tout if not having big media files? 10,000 spreadsheets (that might still randomly get deleted)?
I would be afraid to rely on it for business