Custom Tab Title and Favicon od Guy de Pourtalès

Custom Tab Title and Favicon is a Firefox web extension that allows setting
rules to change the title, and the favicon of any tab based on
regular expressions applied to the URL or the title of the tab

You can also insert dynamic values in the custom title like dates or hostname.

Settings page can be accessed through the sidebar, the toolbar or in the preferences page of the extension.

Please see full documentation here

Sync support

This web extension stores the parameters in the synced storage space. The user can then share the settings
in all synced firefox instances.

License
This web extension is distributed under the Mozilla Public License Version 2.0 (https://www.mozilla.org/en-US/MPL/2.0/)