Path-Tracing Renderer - Machinima

How can I get rid of the fake shadows on flat surfaces when using RTX Interactive (Path Tracing) renderer. When my camera is close to the horizontal surface (Earth) the rendered images include a lot of fake shadows and they change from frame to frame. So the resulting video icludes a lot of “shivering” fake shadows. I use “Path Trace samples per pixel (per subframe)” 128 and motion blur is off.