Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. Is the problem still there?

What permission are you talking about?

You can inspect and manage permissions for the domain in the currently selected tab via these steps:

• click the "Site Identity Button" (globe/padlock) at the left end of the location/address bar
• click the arrow to expand the security message
• click "More Information" to open "Tools > Page Info"
• click "Permissions" to inspect and modify permissions
• click "Security" to inspect and modify cookies and passwords in a standalone window

Go to the Permissions tab (Tools > Page Info > Permissions) to check the permissions for the domain in the currently selected tab.

You can rename (or delete) the permissions.sqlite file in the Firefox profile folder to reset all permissions stored in this file or alternatively clear the Site Preferences via Clear Recent History.

Clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, passwords, and other website specific data.