Earlier quoted context omitted.
This was my first response as well (it's not the data sharing that's the problem, it's that you noticed). Thinking about it though, a lot of it is a question of surprise and unknowns. I would find this message to be a lot better - "We see that you've taken advantage of the Ubuntu image that Canonical provide in the Azure Marketplace. I am available to you for (etc.)".
> * I would find this message to be a lot better - "We see that you've taken advantage of the Ubuntu image* No. That's not better at all. The mere fact that Canonical has specific information to reach me when I am not a direct customer of Canonical is a complete violation of my privacy. Ubuntu is a free product. Canonical should not be able to find out if I (specifically me or my organization) allocates or runs 1 or…
In this case, the license is the GPL, none of which has anything to say about privacy. Maybe this is a failure of the Free Software Foundation's to not include privacy protection in the GPL. Though even if they were to create a GPLv4, the Linux Kernel is still only licensed under v2, so distro implementors have no obligation to use a more restrictive license.
AKA, "the cat is already out of the bag".
In the OP's case, they additionally are are customer of Microsoft's, who explicitly stated they share this kind of information with their vendors.