Immediately after Windows 10 2004 is installed it downloads AMD Graphics Drivers v.18 from Windows Update, installs it and doesn't allow to install Catalyst 20 ending up with some error during Catalyst 20 installation.
I think Catalyst 20 installs some, may be even all of its parts, because RX 540 becomes 500 Series after Catalyst 20 installation stops. But frankly I absolutely do not want to use drivers which installation was interrupted.
In case I prevent Windows Update by turning off internet connection during installation of Windows 10 2004 and install Catalyst 20 immediately, it installs successfully and working properly until I connect back to the internet.
As soon as Windows discovers it can self-destroy again, it connects to Windows Update, downloads AMD v.18 drivers and installs them over v.20 making either the AMD Control Center or some AMD app downloaded from the Microsoft Store inoperable because of the versions conflict.
I understand that I should address this question to the AMD and Microsoft techs also, but in case you will take a close look at the attached screenshot, you may notice quite a strange string among updates Windows thinks I must install on my NUC8i3CYSN. May be those cases are connected some way. Anyway I've purchased the Intel's thing, not AMD's.
All above problems do not exist in Windows 10 1909.
My experience was different. I installed the Radeon 20.4.1 package first (just by happenstance). I then updated to 2004. Upon opening the Radeon Software app (from the System Tray icon) today, I was informed that I had a version mismatch and that I should install the latest Radeon package from scratch. I downloaded and installed 20.5.1. Windows Update then installed a small AMD MEDIA update, but this (whatever it is) doesn't seem to have touched anything. Nothing to do with NVIDIA is mentioned, installed, or identified for update by Windows Update. Running Intel Driver and Support Assistant, only an update for Optane was identified.