Rated 3 out of 5 stars

Disabling and removing Cardbord extension, both help that the Thunderbird "Send Button" in the Email writing Dialogue works again. A funny quote from AI:
“Please try pressing the button again, ensuring it is fully depressed.”

This review is for a previous version of the add-on (95.3). 

after the available 95.5, a new version is instance of approbation which fix most the known bugs (95.6 here :https://addons.thunderbird.net/fr/developers/addon/cardbook/versions/2491083)

if you have remaining issues, please open a ticket here : https://gitlab.com/CardBook/CardBook/-/issues