I have a self-hosted Baikal server with self-signed CA on Android 14 and it works.
However, I didn’t had to add the certificate to Davx⁵ itself. Adding a rootCA into your device and your reverse proxy handling the request should work as expected over https.
Those kind of things are difficult to troubleshoot, this could be:
Bad rootCA certificate, missing the necessary options ?
Wrong certificate handled by your reverse proxy ?
Radicale doesn’t recognize your certificate extension ?
Wrong networking configuration ?
Bug ?
…
We need more infos about your setup:
Do you use a reverse proxy ?
Had you already any success with this certificate within an other application ?