That is not necessarily true for Freenode or Libera. Client connections over TLS are encouraged, and I'm pretty sure that server-to-server links are all over TL

That is not necessarily true for Freenode or Libera. Client connections over TLS are encouraged, and I'm pretty sure that server-to-server links are all over TLS also. Plus, there are some controls for users and channel admins to make sure they are talking over TLS only, such as +S channel mode, which only lets in TLS-using client connections to join.