Issue in small screen camera while on whatsapp video call

During a video call via whatsapp in iphone 14 pro ios 16.1 when the call is initially connected, both the front as well as the back cameras are displayed in the big and smaller screens respectively. When I click the smaller screen, camera switched just fine. When I click on the smaller screen again, the camera switches fines but the smaller screen greys out. It stays grey when clicked as many times but the camera switches just fine.