Whether “end-to-end encryption” is the 100% accurate description is actually secondary to understanding how something like this is set up. 😉
If you search for [hdcp googled](https://www.google.com/search?q=hdcp&sxsrf=ALiCzsaeDXHg35I54nD4DFyUj__RAzKpiQ%3A1652979510421&ei=NneGYrnW F5Th7_UP4PqM4A0&ved=0ahUKEwi5yabEhOz3AhWU8LsIHWA9A9wQ4dUDCA4&uact=5&oq=hdcp&gs_lcp=Cgdnd3Mtd2l6EAMyBAgjECcyBAgAEEMyB QgAEIAEMgsIABCABBCxAxCDATIFCAAQgAQyBQgAEIAEMgUIABCABDIFCAAQgAQyBQgAEIAEMgUIABCABDoRCC4QgAQQsQMQgwEQxwEQ0QM6BwgAELED EEM6CggAELEDEIMBEEM6CAgAEIAEELEDSgQIQRgASgQIRhgAUABYpglg9gpoAHABeACAAYQBiAGMA5IBAzIuMpgBAKABAcABAQ&sclient=gws-wiz), This text appears very prominently: "HDCP stands for “High-bandwidth Digital Content Protection”, which translates as “protection for digital content with high bandwidth”. The process developed by Intel in 2003 is therefore a type of copy protection."
It’s not primarily about end-to-end encryption, but rather about ensuring that only authorized devices are allowed to pass on and process the transmitted data. If a device reports “I can’t do anything with that” or “huh, what do you want from me?”, the transmission is interrupted; It doesn’t really matter how the data gets from A to B. The source <-> image playback chain must therefore fully support DRM/HDCP.
And viewed this way, one might be inclined to call this end-to-end encryption, because without decryption at the end no image arrives, or at least not one that we would like to see.