Account has been locked twice in short time and I don't understand why

Today my account has been locked a second time, exactly one month after it happened the first time and I don't understand why.

All things started when I changed my primary account from *** Die E-Mail-Adresse wurde aus Datenschutzgründen entfernt. *** to *** Die E-Mail-Adresse wurde aus Datenschutzgründen entfernt. ***. Everything was fine for three days but then my account was locked due to "unusual activity" or due to "violating the tos". I've been using my account for more than a decade without any problems so I was curious to know why it happened so I contacted support.

Support was no help as they weren't allowed to tell me anything because of privacy concerns so I contacted the Microsoft privacy team/department. After a day I got an email that told me I had violated the tos but the email did not provide any details to what exactly I had done wrong.

The mail included a copied/pasted part of the tos: No account sharing, no spam, etc.

Again no help, because I didn't do any of those things.

Let me be claer:

- I've used the same account for more than a decade, mostly for Xbox but also for other devices/services such as One Drive, Windows Phone etc.

- I've never shared account information with anyone. I own several Xboxes which are in different rooms in my house, which get usage on different occasions, all part of the insider program. I have a One Drive which I access from PC, tablet and phone. One month after launch my Series X died and I had to send it in for replacement. I wasn't able to remove my account as it didn't power on but I removed the device from my account through the web.

- The gmail-address was a unique email used for my Microsoft account, that was used nowhere else, the same goes for the myowndomain.net email.

- I've been using 2FA since it is available. I use Microsoft authenticator.

- My account hasn't been compromised, I checked the activity. Still I changed my password.

- I don't use a VPN to connect to Xbox or any other Microsoft services.

- Over the years I've collected a massive library of digital games so of course I'm worried about this situation.

- I've never experienced any payment problems with my PayPal or with the gift cards used. I don't use gift cards from shady resellers. I'm currently subscribed to a service.

- I've got a Gamertag that is considered desirable. In the past people messaged me trying to get me to change the tag or tried to buy it from me. I never replied to these messages, I usually ignore them or report the users that sent them. I also get added by random (bot?) accounts every day. Other users (don't know if real) shared my community posts in the past. I don't know those users nor do I know the place the content has been shared to. That's the reason I changed my profile private/friends only.

I'm at a loss here...I don't understand why my account suddenly gets locked and I feel like the Microsoft support channels are no help. I want to know what the problem is and how to solve it. I also want to know if these account locks have any negative side effects to my account status, e.g. if those locks result in a "bad standing" of the account.

After the lock that occurred today I have reverted my primary alias back to my gmail and removed the myowndomain email from the account, as it first started happening with the change. I also changed my password. Again.

I don't recall any notification about violating tos this time though...my account simply got locked one month after it happened the first time.

So...again: Why is this happening and how do I stop it?

:)