Ventura & OneDrive - hidden duplicate local files?

Good afternoon,

I recently updated to Ventura on my MacBook Pro.

I use OneDrive for work, and have about 110GB of files stored in my OneDrive folder, being continuously backed-up. These files were always saved locally on my computer (...I never use Files-on-Demand as I'm frequently offline but still need access to all of my documents).

Upon updating to Ventura, I found my local OneDrive folder was totally empty. I had a quick check and found all of my files still backed-up online (phew), but this didn't explain the empty local folder. It looks like, somehow, during the update OneDrive switched itself to Files on Demand..?

Okay, fine, I've switched OneDrive back to local file storage.

HOWEVER, prior to the update I had 128GB of empty storage on my MacBook Pro. Now that I'm re-downloading all of my OneDrive files locally, this has dropped to just 18GB. Yet these files were stored locally before the update, and I still had 128GB of space.

So it looks like OneDrive has duplicated the files on my system, but (1) I can only see one copy, (2) I can't delete the second copy, (3) I have no way to know if this is true or not, but I can't see where else that 110GB of storage has gone.

This is crippling my storage and I can't find a solution elsewhere.

Any advice on this?