I have the same problem and thanks to this thread I was able to find out what the problem is. My Tapo cameras are connected via WebRTC and as soon as I watch the live stream it seems to continue running in the background.
My problem is that it is not enough to leave the view and then close the app. It still uses battery. Despite WiFi and mobile data being turned off, it was 40 percent overnight! 7 hours of background activity.
Is there a trick I can do to stop this? Not being able to use the cameras anymore would be a shame.