In the working directory of the Moonlight.exe in the latest Moonlight-xxxxxxxxxx.log you can find:
00:00:01 - SDL Info (0): GPU driver: igdumdim64.dll 20.19.15.4377
00:00:01 - SDL Info (0): Detected buggy Intel GPU driver installed. Update your Intel GPU driver to enable HEVC!
To solve this issue install a newer driver from Intel: https://www.intel.ru/content/www/ru/ru/download/19344/intel-graphics-windows-dch-drivers.html