In macOS Big Sur, firewalls like Little Snitch or Lulu were unable to block Apple's own services from phoning home. That has now been fixed in the latest beta release and will work as it did before soon. You can see this article for details. [1]
I am 20+ years on Apple products. This is not the way for me.
I cannot trust them anymore. If I have payed for my computer and the vendor is using it without my permission - there is no fix for this. What's next? Jailbreaking Mac OS? I don't care for Apple apologists or cultists, they have a right to choose. My choice is to move away from Apple products and replace everything that I can with Linux and FOSS.
[1]: https://www.macrumors.com/2021/01/14/macos-big-sur-11-2-beta...