It depends what you consider data, to me for example, all the devices I use in my home, who comes in my home and such are considered private (as it should, but we might disagree on this), but realize that the moment someone steps-in your home, then the typical correlation of SSIDs, BT devices (to simplify it) is sent as telemtry to MS servers (this is official, I'm not just speculating).

And about pure "data" as in filenames file content and such, then obviously typical Windows Defender, Smartscreen and such that would send file hashes, sometimes content, filenames, mod time and such, making Microsoft directly aware of your filesystem content.

I'm not dying on a hill. From a security standpoint, every "trust" step is a security assumption that you cannot verify (especially on a Samsung phone), I'm just not willing to bet my threat model on the "goodwill" of a corporation whose business model is built on data aggregation, there is no proofs needed (MS has had a ton of breaches the last decade btw), but you do you.

Let me ask you something and make an hypothetical and you must reply in good faith, this is because we don't agree on fundamental points on security:

If you were a wanted criminal that still needs to work online somehow to make money, would you feel safe using Windows?

I think we can agree that privacy and security are heavily intertwined. If your honest answer is no,then that alone tells you something about the OS trust model. And if your answer is "yes", then i'd genuinely like to hear why, because I can't think of a single compelling reason.