Apple’s stance is not all E2EE is off by default… Instead there are a set of things which are E2EE when you are using Standard Data Protection and a wider set of things become E2EE when you opt-in to Advanced Data Protection.

This is all clearly documented here: https://support.apple.com/en-us/102651

What’s changing is the UK government is apparently serving a Technical Capability Notice compelling Apple to provide access to their customers data, and the only reasonable way for Apple to comply is to remove ADP as an option in the United Kingdom.