Why is GnuTLS so poor?

Question

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Salute comrade!
Actually the problem: there is mutt to which I send reports from everywhere, there is a config that has been tested for years. A couple of rpm-base servers have appeared, and mail is not leaving them. Neither mutt nor ssmtp. I started to study the issue, and it turned out that all the software in rpm-base was built with "-openssl + gnutls". And now how to make this not a miracle work? in the mail logs, when sending from a normal place, I have

Anonymous TLS connection established from unknown[xx.xx.xx.xx]: TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)

and everything is running great.
When sending from rpm-base

Anonymous TLS connection established from unknown[xx.xx.xx.xx]: TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)
lost connection after STARTTLS from unknown[xx.xx.xx.xx]

How to be? How to defeat him? How to make it work properly? Rebuilding is not an option, because since this gnutls exists, and the entire system is assembled with it, then it must somehow work?