This is the post on the OpenBSD subreddit that prompted this list post: * https://old.reddit.com/r/openbsd/comments/shgdp0/xmppserver_with_openbsd_prosody_someone_getting_a/
It appears that whatever the IM Observatory is using for TLS root certificates was not been updated to accommodate the root certificate expiry that Let's Encrypt experienced at the end of September. For example, OpenBSD keeps such root certificates in /etc/ssl/cert.pem and failure to update this file causes current Let's Encrypt TLS certificates to fail. Thanks!
