Hello JayTZ,
Thanks for posting in the Apple Support Communities.
We understand you've noticed an issue with using Bluetooth headphones in Microsoft Teams on your iPhone, right?
If we understood that correctly, let's confirm the latest iOS updates have been installed along with app updates via the App Store. If an update is available for iOS, be sure to back up your information before installing. For assistance with backing up and installing, check out the following steps: Update your iPhone or iPad - Apple Support
Update your iPhone or iPad wirelessly
1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. Choose the software update that you want to install. You can choose to stay on iOS or iPadOS 15 and still get important security updates. Or you can choose the option to upgrade to iOS or iPadOS 16.

5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.
If you're up-to-date with the latest iOS version, let's check the App Store for an update to Microsoft Teams. For assistance with updating your apps, take a look at the steps of this resource: How to manually update apps on your Apple device - Apple Support
Should you need further assistance, try restarting your iPhone to see if this continues to occur with different Bluetooth headsets. If it still occurs with the Microsoft Teams only, we'd recommend working with Microsoft Support.
Have a great day!