Video calls are not minimizing

Hello Blueline9,

Welcome to Apple Support Communities!

We want to help you get the most from your iPhone and use Picture in Picture.

This feature is not compatible with all apps. See here for more details:

"Multitask with Picture in Picture on iPhone

With Picture in Picture, you can watch a video or use FaceTime while you use other apps.

While watching a video, tap 

The video window scales down to a corner of your screen so you can see the Home Screen and open other apps. With the video window showing, you can do any of the following:

• Resize the video window: To make the small video window larger, pinch open. To shrink it again, pinch closed.
• Show and hide controls: Tap the video window.
• Move the video window: Drag it to a different corner of the screen.
• Hide the video window: Drag it off the left or right edge of the screen.
• Close the video window: Tap .
• Return to a full video screen: Tap  in the small video window."

Explained on this Apple Support page Multitask with Picture in Picture on iPhone - Apple Support

If you feel the app isn't working as expected, you might want reach out to the developer directly to see if the app is compatible with the feature.

We hope these steps can help isolate and resolve the issue.

Cheers!