Comment by calebio

It wasn't coined, it was reused. It historically meant things that were encrypted from the client to the server, e.g. SSH, SSL, TLS, etc.

RFC 4949 (Internet Security Glossary, Version 2) from 2007: https://datatracker.ietf.org/doc/html/rfc4949

     $ end-to-end encryption
      (I) Continuous protection of data that flows between two points in
      a network, effected by encrypting data when it leaves its source,
      keeping it encrypted while it passes through any intermediate
      computers (such as routers), and decrypting it only when it
      arrives at the intended final destination. (See: wiretapping.
      Compare: link encryption.)

      Examples: A few are BLACKER, CANEWARE, IPLI, IPsec, PLI, SDNS,
      SILS, SSH, SSL, TLS.

      Tutorial: When two points are separated by multiple communication
      links that are connected by one or more intermediate relays, end-
      to-end encryption enables the source and destination systems to
      protect their communications without depending on the intermediate
      systems to provide the protection.

There's a bunch of older references as well. Since SSL/TLS wasn't really adopted by a lot of services until 2008+ usages of it are mainly in papers, old forum posts, etc. I saw it used and was discussing it back in the day on IRC with folks who were way more knowledgeable than me on this topic and had been in the trenches for a while :D