> The E2EE in Signal only protects the actual content of messages.
> [By] (simply saving the data) Signal could get access to things like contacts and phone numbers.
And the linked blog posts show that for a few years now they've been working on limiting their own access to this kind of data --- i.e. it's not as simple as just saving it (like e.g. WhatsApp is able to and most likely doing 100% of the time to build social graphs).
Now of course all of those things are likely vulnerable to some attacks, but that's another discussion and it doesn't change the fact that Signal doesn't have immediate easy access in the way you claimed in your original comment. The fact is that there are some barriers and they'd have to put some effort into either disabling these protections or exploit flaws in them to get to the data.