TLS 1.3 has been finalized, OpenSSL v1.1.1 has been released and thus it is time for you to upgrade. I hope you can thereby remove many legacy ciphers and such stuff. If this is done at some point in the future, the next step is obviously to deprecate/remove older TLS versions like TLS 1.0 and 1.1 (I assume/hope you do not SSL anymore.).
As far as I can tell, kdeconnect doesn't implement this itself, it uses Qt's support for this. (If so, this bug is misplaced)