What's with that weird stripe above the Finder icon?

Question

macOS

Hello, I have a problem that I can not solve for a month.
A strange translucent strip has appeared above the finder icon in dock-e and it does not disappear. I don't even know what to do with it. Tell me please, who can come across.

Answer 1

- turn off the computer,
- then turn it on again,
- as soon as the standard sound plays when you turn it on, press the shift button, and then release it as soon as an apple appears on a gray background.
- reload
do it - otherwise, over time, finder will stop opening when you click on the icon