So, the issue seems to be related to an external element. If you move the phone away, does your PC flicker?
it depends on the distance to the screens. the closer i put my mobile to them, the worse it gets.
the flickering starts if i put my active mobile closer then 60 to 70cm to the screens, further away is no problem.
This can be addressed as en external issue, from your description the graphics controller and the Intel® HD Graphics driver are working fine, so the issue is regard to your phone not the graphics controller. Maybe it's just your phone and some kind of interference.
Closing this as HW issue. This is not related to Intel Graphics, please seek assistance from the OEM.