Which certificates with prosody

Using letsencrypt that is being used by the jitsi frontend.
However prosody uses a self signed one?
In /etc/prosody/certs/ there is
example.com.crt / key and auth.example.com.crt / key

Can’t letsencrypt ones be used for these? Mostly interested in this while adding videobridge2 nodes using the muc method, and it fails the certificate checking. One tutorial said to disable certificate checking and this works but i’m not sure this is a good idea.