Having issues with Google Drive syncing?

I’ve been relying on Google Drive for years now—it’s been smooth sailing until just a few days ago.
As most of you probably know, the whole point of this setup is that anything I drop into my local Google Drive folder on my PC automatically uploads to the cloud, making everything accessible from just about anywhere.
However, when I logged onto the web interface today, I realized that three or four folders I moved into my local directory a couple of days back are simply missing from the online view.
I’m honestly at a loss here—everything is configured to launch Google Drive right alongside Windows at startup.
If I check the system tray, the Google Drive icon is sitting there perfectly fine, and it even explicitly states "sync complete."
Does anyone have any insight into why my local files aren't matching what I see on the web?

What on earth is going on with Google Drive lately? I’ve been seeing a massive wave of people complaining that their Drive has gone completely haywire—syncing just refuses to work—and they keep getting hit with this specific error message:

Sorry, Google Drive needs to quit.
An unknown issue occurred and Google Drive needs to quit. Error: 4ADB

I have spent quite a bit of time digging through various troubleshooting tips online, but honestly—to my frustration—none of them seem to actually fix anything.
Does anyone happen to know what might be causing this mess?