Updates for Teams can roll-out gradually, so you may find your version isn't as up to date as someone elses.
You may want to check for any available updates, to do this in the teams App, click on your profile picture/initials in the top left and choose Check for updates:
Teams will then check for any available updates and apply them. You will see this in a grey banner at the top:
You may find however that the most recent updates are still not available, in this case check to see if you have an option to turn on the new meeting experience. To do this, click on your profile picture/initials again, choose settings, then under the application options you can tick Turn on New Meeting experience. You will need to close and restart teams for this to take effect.