iCloud is not E2E, unless you consider "end-to-law-enforcement-to-end" E2E. [1]
In fact, Apple were going to do this but caved under pressure from law enforcement.
Imagine being an Apple engineer having joined a "privacy company" and then being forced to desecrate your users privacy in innumerable ways.
[1] https://www.howtogeek.com/710509/apples-imessage-is-secure.....