Teams invites random people to meetings

You are probably selecting a channel to have the meeting in when creating the meeting, assuming you do it inside Teams. Do not select channels cause the meetings are not private at that point and some people could in fact get notifications if the attached group setting has notifications on, and they will see the meetings take place in the channels when they take place.

It's that, that is going on, or the only other thing outside a serious bug would be that the people you invite have delegates setup for their account and the meetings get forwarded to someone else, but based on the problem statement above it looks like you are selecting a channel to hold the meeting which makes the meeting public, leave that field empty so meetings are private or utilize Outlook to schedule Teams meetings since that doesn't let you do that.