iCloud & iCloud Photos · Storage Studio and iCloud
What happens to my iCloud files if I uninstall Storage Studio?
Short answer: Nothing. Files Storage Studio made online-only are still in iCloud and download when opened, downloaded files stay put, and iCloud keeps syncing through macOS. Use the uninstall wizard for anything relocated to your fast drive.
Nothing. Your iCloud files never depended on Storage Studio: files it made online-only are still in iCloud and download when you open them, and downloaded files stay as they are. iCloud keeps syncing through macOS as usual.
Storage Studio doesn't store iCloud files anywhere special, so there's nothing to restore. Duplicates you removed earlier are in the Trash until it's emptied.
For other things Storage Studio manages — such as folders relocated to your fast drive — use its uninstall wizard, which helps move them back first. See getting started.