macOS — What is the reason for a 6 Gb Dropbox folder to use 107 Gb of space?
Dropbox, OneDrive, iCloud and other could sync programs often show different sizes on one file. You want to check a few files to look at the size on disk as well as the settings about saving space / dehydrating files / optimizing storage before trusting any one tool to measure on disk allocation.
I use ncdu on Macs where I have homebrew running or du -s /path/to/folder to double check things. Finder and even Apple’s system information don’t always tell the true story with cloud files.
You can also get a good measure by using Time Machine to back up the folder and checking size there.
Assuming you are actually that far off, the fix would be to boot to recovery and run disk utility one time on the drive to correct and detect any accounting errors, then potentially uninstalling the sync app to clean up the folder.