I have reboot my OS 10.14.6 (18G84) and see some strange stripes, it is not connected to Mac book screen as you can see I opened Downloads and all looks good on the second image I've attached.
What can be a problem?
when I switched to static desktop image this problem disappeared, but it's still there when I switch to dynamic desktop.
Also I've deleted cache in ~/Library/Caches on my MacBook as my Mac was freezing and I also disabled spotlight for SSD. Maybe this somehow affected on the issue.