#Firefox #matrixchat protocol handling question. #Linux #Debian, FF 115.14.0esr

I used to have a matrix client configured in firefox to handle matrix links like matrix:#recepcja:synapse.tepewu.pl .
Then I replaced that client with Element-desktop and have no way to change the delegation.
In config: zone, there is only a boolean matrix=True, nothing else. If I try to add "another app", the path /usr/share/applications/element-desktop.desktop is ignored.

Hjalp, pleese?