Rated 5 out of 5 stars

The extension works for me on macOS 11.7.4 and Thunderbird 102.8.0. However, I had to uninstall and reinstall the extension twice (including restarts of Thunderbird) before it actually worked. After the final reinstall I got to see an "Add-on Options" icon (a spanner) in the Add-ons Manager that was not there when the extension did not work.

This review is for a previous version of the add-on (3.8.10). 

the spanner/wrench problem is actually a TB problem (not addon), as I learned a few days ago from TB developers.
Another workaround is to close the addon tab and to reopen it. Then, the wrench comes up as well.