Earlier quoted context omitted.
Try having a kid and segregating funds for them while paying for their Xbox Game Pass and a Minecraft Realm with your account. I have 25 years of Windows software development experience and I was almost reduced to tears just trying to understand what I'm even trying to accomplish. Realms is still in some kind of half subscribed, half not subscribed state and it still asks for my account's PIN for purchases but actual…
I witnessed an egregious bug once - where logging in with one users name and a different users 2FA let me in. I just looked for my notes on it and can’t find them. I’m happy for you not to take my word on it other than to say — I concur that there are some egregious bugs in this area!
I have no idea where to report the issue to (Microsoft store? Minecraft support? Microsoft Windows support?), and having dealt with Microsoft support in a professional capacity I know that even if I do figure out where to report it that they will waste weeks of my time asking me to explain the issue and then claim it's working as designed without understanding the problem at all.