Clear browsing data with a single click is a great idea but it doesn't work for me. Checked all the extension settings and tried it out multiple times.
Having "Cleared Browser Data" with the extension toolbar button I then look into the Firefox settings and there are still cookies and other saved data sitting under the "Manage Cookies and Site Data" heading.

"Clear Browsing Data" indicates that it has cleared everything multiple times. When I go to Firefox "Settings-Privacy & Security" I still have cookies and storage items from Google (and occasionally other sites) that must be cleared via Firefox settings.

Not working. I tried to remove all data, then open devtools and found cookies, localstorage data and so on

Deletes site data of all websites including history. This option should not be default or at-least there should be warning. I'm now using "Cookie Quick Manager" which allows choosing which ones to delete.

Unexpectedly deleted ALL data for ALL sites including history! Very frustrated! I thought this would be on a per-site basis, and now don't have site autocomplete for a while.