Gaming PC is abnormal?

I need urgent help.

For some days my gaming PC is not working properly.

I once went into the device manager and looked at the processor, graphics card, etc. (out of interest), since he does not work properly.

I play, for example Fortnite now only with 20-30 FPS, but before that it was 120 FPS!

The CPU percentage has also increased a lot! For the Epic Games Launcher alone, the CPU is up to 100% (if it makes an update) and Fortnite is exactly the same. I'm desperate because my PC is just 4 months old.

I would really appreciate help.

This is a launcher, which only makes an update!

Why is the GPU load on Firefox 100%? That would be much more interesting to know

Do you have the latest motherboard drivers installed?

Have you done a complete virus scan recently?

Which anti-virus program do you have?

Which hardware do you have?

Only watched YouTube, but nothing more. : I

So if I watch Youtube then my GPU on Chrome is just 6%

Graphics card drivers are up to date?

Yes, I just looked, everything up to date.