I'm confused with the available and available offline status of my Windows files/folders.

Sending a help ticket as I guess I won't be getting an answer here. :(

Ticket text: Dropbox updated to a Windows 11-compatible version last night and started resyncing everything. It seems to be downloading everything and now my hard drive is almost full. I don't understand what's going on. I'm pretty sure I have selective sync turned on (Dropbox is set to sync only certain Dropbox folders) but can't check anymore. I've marked the folders I want to be online only as online only so I should not be out of room, but as long as Dropbox keeps running and syncing, my computer is going to fill up and crash. It had around 200GB left to go when I turned it off; I have over 1TB on Dropbox, and my hard drive is only 500GB and is nearly full.

I can't update my files anymore like this. I've had to turn Dropbox off completely and am afraid to turn it back on if it keeps doing this. I have more Dropbox space than computer hard drive space.

Edit, I closed Dropbox and restarted in case the "downloaded" files were merely cached, but my drive is almost completely full and Windows is sending warnings. I'm on Windows 10. If I turn it back on to finish or to try again to mark things as online only, my computer likely can't take it. I also have no way to see what has actually downloaded, as the big online only folders that are the most likely culprits were still syncing, so I don't know that uninstalling/reinstalling would work, something unknown is already taking up hard drive space, and it will resume doing so when I turn it back on. How do I fix this?

(EDIT unrelated to my request, but ugh, this forum has become nearly unusable, all the page elements takes so long to load I keep wondering if the site's even working.)