Hi, I'm John! I will help you with this.
If you haven't tried anything yet please start by:
Check your account rules and forwarding settings. You can do this in Outlook settings under Mail > Rules and Forwarding. https://support.microsoft.com/office/manage-email-messages-by-using-rules-in-outlook-c24f5dea-9465-4df4-ad17-a50704d66c59
Just to be safe, I’d recommend to sign out everywhere. Visit: https://account.live.com/proofs/manage/additional Scroll down to Sign me out and select "Sign me out".
After signing out everywhere, please monitor if the issue persists in the coming hours.
I really hope this information is helpful! Let me know if you have any further questions or concerns.
Regards,
John J.D.