Microsoft Teams meetings are great in that you can join on one device (like your Teams desktop client) and then switch over to using your iPhone to listen to the meeting if you have to walk away. However, if you join the meeting from a second device (instead of switching devices), it can be hard to completely leave the meeting on both devices. Teams now allows you to leave a meeting on all devices when you’re ready to exit the meeting. Here’s how that works…
In this meeting example, I’m in the meeting on both my Teams desktop client and my iPhone. When I get ready to Leave the meeting on my Teams desktop client, I have the option to Leave on all my devices. That will stop the meeting on both my desktop client and the iPhone:

If I Leave the meeting on my iPhone, I have the same option there:

So you may wonder why you’d in a meeting on two devices to begin with. One example is you may have been recording the meeting on your Teams desktop client, but you had to switch over to your iPhone as you needed to step away. You want to keep the desktop meeting experience running for the recording, so you can’t switch devices. You have to join the meeting with the other device so the desktop client keeps recording so long as it’s up.