This is a convenience feature in Outlook that is enabled only if you have a Teams licence, specifically that when you create a meeting in Outlook, it sets it as an online meeting.
You can turn this off, but last I checked can also set it to stuff like Google Meet, Zoom, WebEx, Facetime, etc if you have the relevant plug-in for Outlook.
You can turn this off, but last I checked can also set it to stuff like Google Meet, Zoom, WebEx, Facetime, etc if you have the relevant plug-in for Outlook.