HP Omen 17 having issues with high CPU usage & brightness/battery/airplane mode in Windows 11

[MuhammadAA]

After moving to Windows 11, I'm often noticing that my system process keeps using around 13-17% CPU constantly. It goes on for hours and just doesn't stop. Restarting doesn't always seem to fix the problem. The only solution seems to be to shutdown and start the laptop all over again. When I do that, the system process returns to its regular 0-2% CPU usage. Already tried all the usual solutions like disabling fast startup, installing drivers, resetting Windows, etc., but to no avail.

I also checked the threads in Process Explorer, and the culprit is always acpi.sys+0x25550. I'm at a loss regarding how to fix the issue. Shutdown seems to be better at fixing the problem than restart. Even resetting Windows 11 didn't work (full reset without keeping files in OS drive), and I've installed the latest drivers provided on the laptop's support page. My laptop is HP Omen 17-an013tx.

There are also three other MAJOR issues that are seriously problematic and a real nuisance (probably worse than the system process issue). The brightness level randomly jumps up and down by itself. Airplane mode also keeps going haywire, toggling on/off, while Windows also keeps losing track of the battery (when this happens, it stops detecting battery percentage correctly and can't even tell when I take out the charger, so it continues working as if plugged in instead of turning on battery saver, etc.). 

Someone on Reddit said that it's a BIOS issue (I've also tried resetting BIOS settings and installing an older BIOS version but it didn't help). The poster on Reddit said "it's your BIOS then, there should be a setting in your BIOS to change the power management. I'd suggest contacting HP and get them to check your BIOS settings for Power Management." It's been several days since I moved to Windows 11 and I really need a proper, permanent fix for these persistent issues. Surely HP Omen 17 should be capable of running Windows 11 without all these absurd problems.

[MuhammadAA]

One thing I noticed is that when I run the driver check on HP's support page, it keeps detecting that a DisplayLink driver update is available, though I've definitely installed the latest version of the driver (multiple times to see if the page detects that it's installed), so maybe its installation is failing for some reason. However, I doubt it has anything to do with the issues I mentioned in the OP.