This extension would be great if it worked, the possibility of whitelisting or blacklisting domains or subdomains is missing in most data clean-up extensions. Unfortunately, it doesn't work at all.
- it disables itself automaticaly at each restart, you have to enable it again in the extension pop-up
- it doesn't register any parameter in the otion page, it always reverts to default
- you have to enable extended permissions in the extensions tab.
- even with these permissions enabled, it does nothing after a restart, or when closing the tab, or when selecting "Clean the current domain" or "Clean the current tab", no cookies, no data are deleted.
- the extension's repository on Github, github.com/o2Cloud-fr/o2Clean has been deleted/closed so it means there's a big problem here

So I gently suggest the developer to fix it or delete it from the Firefox addons as it's useless in it's current state and gets the users to lose their time installing and testing it. Honestly I really don't get it as it's not an old extensions and obviously a lot of work has been put in it...

Firefox 149.1esr