Compromised Account Concern

Hi,

I've recently had my email account hacked which they then used to reset passwords of many of my other accounts. I have since recovered my email account and secured it with 2FA, new password and new alias as well as force sign out of all apps and devices option from within security settings.

The concern I have is that when I go to my mail on the web, go to settings > general > mobile devices, From time to time a new device shows up as IOS 17.5.1 with no Phone number or Device IMEI. I have skimmed through my devices and I cannot identify this device, especially since I do not own an iphone or apple product altogether. I'm concerned about this because the status is OK with Access State: Access Granted. When I go to security > recent sign-ins, I only see attempts and successful sign-ins from my actual IP and devices.

I've attached a screenshot of what of what I see. How is it possible for a device to still gain access even though I've enabled 2FA on my actual phone ? Or is this just being seen as coming from one of the outlook apps I use on my other 2 devices (laptop and PC) with misread information? What can I do about it ?

If anyone has encountered this before, I'd appreciate some information as I'd like some peace of mind. The way it stands, I keep checking my account every hour around the clock and select Wipe all data as well as remove the device from the list when it does appear. But so far I've done this at least 4 times within 48 hours.

Much Appreciated.