There seems to be an occasional bug with creating a new event from my email window (using the plus sign on the right side bar).
When I check the box that says "Teams meeting," sometimes in the process of editing other information, the Teams meeting checkbox will become unchecked and I will then unknowingly send out the invite with no Teams meeting included. It doesn't happen consistently, but it has happened to me more than once. It seems to happen when I either add a comment in the notes field (sometimes, but not always), or when I edit the recipient list of the invite (again, not always).
It's an annoying bug, because sometimes I'll not even realize until right at meeting time that there is no Teams meeting scheduled.