Thanks for the feedback. That would be useful, but it is a different cleanup mode from what the extension currently supports.

Firefox’s browsingData API works with “clear data since this time”, which fits options like last hour, last 24 hours, or all time. “Delete data older than X days” is not available for every data type, especially cache and site storage.

I’ll keep it in mind as a possible future option for the data types where Firefox supports it, such as history.