Chatty with private CA?

I created a private CA and signed the certificate for my XMPP server with it.
I used update-ca-certificate to import the CA on my client machine. (Librem 5 and also Debian 11 Laptop)

This works well with Dino as client. (only tested on the Laptop)
But with chatty I always get an invalid certificate error.

Has anyone a similar setup running and a tip how I get chatty to accept the certificate of this CA?