Our domain address is detected as Phishing in microsoft

We use Microsoft Exchange Online as the mail system of our domain and hosting in Natro.

DKIM, SPF and DMARC have been active in our mail system for 1 year without any problems.

When we query our domain address with tools on the internet, there is no blacklist.

While our text-only mails are delivered to the recipients without any problems, mails containing our own domain in the mail body are detected as High Probability Pishing in recipients using Microsoft infrastructure and our mails fall into the recipient's quarantine.

There is no problem on the Gmail side.

In our conversation with Microsoft support, he stated that the source of the problem is that we are experiencing this problem as a result of using shared IP on the hosting side.

As a result, we switched to Dedicated IP in Hosting.

From the moment of transition, the problem in all mail flow was solved for 2 days.

However, on the 3rd day, the same problem recurred and the mails started to fall into quarantine.

Our domain was labeled as malicius URL by Microsoft Defender. However, we could not find out what caused this.

I ask for your help.