Anyone can recommend decent free BlueLight Filter App for Win11?

Iam using f.lux now.
Had this problem years ago for some time on different PC. Now, mysteriously, problem came back. At 12 and 1 pm it blinks - shuts itself off for a moment. And it lasts for like 2 minutes. annoying as hell.

Thanks

 

There is a built-in one, just turn on Night light.

 

I have been using f.lux for 10 years now, not with Windows 11 though and I never have this problem. This seems to be a hardware issue either with your screen or a compatibility issue between this software and Windows 11. Did the other PC use Windows 11 as well?