Scaling to the wrong resolution

Hello all,
I am using Teanviewer and Host apps on two Android devices, one is a TV Box running Android 7.1.2 on an external monitor with 1080p resolution and the other is my phone running Android 9 and having an 720p display.
Now while I can fill the 720p with content from 1080p and scaling is correct, when I try the opposite there is a scaling happening making the small screen way smaller on the desktop and trying the settings there is some "Input" option which have some scaling properties but they do not work.
At times when I rotate the phone or run apps, the image flickers a scale to normal for a tiny faction of a second and go back to tiny immedietly, and having only mouse on the 1080p I can not pinch zoom in or out to try and rectify this problem.
It is not normal to scale smaller than window images to even smaller resolution.