255% available (plugged in)

Setting the computer to full performance doesn't do anything if you don't have that power plan in windows power options.

This is how it should look:

This is how mine looks:

As you can see i only have the balanced profile. Changing the laptop to high performance on the little battery icon on the lower right corner doesn't do anything.

I had to manually alter the balanced profile so it works at 100% in the processor power management:

I can't pinpoint it directly to the Nov 2019 update, but I am relatively sure since, I use my laptop >90% of the time on cable without battery inserted and I didn't have this problem in times prior to the update and did not have any other major changes. However, you may be right: I noticed the reduction in performance after the Nov Update, but I can't be sure that the 255% were not shown before... I get the (about) 34% number from the task manager CPU utilization. And yes, I set my windows to run in full performance mode with or without a battery, but the issue remains until I insert the battery. So, I am not sure if the 255% issue is actually causing my main problem, but it seems related.

Sorry, I know all this sounds strange, confusing and vague. I just wrote this here mainly to see if someone else has this strange issue.

@random-name are you sure it worked fine before the november 2019 update? I'm having this problem since either 1709 or 1803.

And where are you getting the 34% performance number? You can force windows to run in performance mode with or without a battery.

It actually does matter in my case. Whenever I have the battery not inserted and the 255% is shown, my computer is capped at 34% of CPU performance. I guess it is due to the "charge" being outside the possible 0-100. When I insert the battery (regardless of charge cable plugged in or not) all is back to normal. This is really annoying and has worked fine prior to the November 2019 Windows 10 Update. However, I can't roll back the update since more than 10days passed until I figured this out.

No, not unless microsoft knows about it and patches it.

And i don't think it ever will since nobody takes it seriously because 1) it's not that serious, it's just a minor asthetic thing and 2) the specialists always think it's related to the specific user and not the OS itself.