Hi,
I kind of fixed the issue. But I do not know what went wrong with the HP driver for AMD graphics.
What I did is:
1. I uninstalled the HP driver of AMD Software.
2. Installed (after factory-reset ticked) the AMD Adrenaline Edition from AMD website.
3. Restarted my computer.
4. Disabled automatic manufacturer driver updates from Group Policy editor in Windows. This will prevent Windows from automatically downloading and installing HP drivers for AMD.
This has solved the high power usage problems. It seems that HP has something wrong with their AMD drivers. When I install the HP driver once again, it creates the same problem. With the AMD Adrenaline software and driver, the problem is fully gone.
However, I still have issues with display brightness flickering in certain games when AMD FreeSync is on. It also happens sometimes when Windows Night Light is active.