When I look at an image at any percent of original resolution I see strange pixelization. As far as I can remeber I didn't have such problem before.
1. 4000x6000. Look at the fingers and edges of the cloth. 20%
2. 1960x2287. Look at the eyebrows and edges of the chair. 35%
When I zoom in at from 60% - 90% of original resolution (depends on image size) everything becomes normal
Think of it this way the only time your are viewing your images pixels is when you zoom to 100% zoom. At any other zoom percentage you are not looking are you images pixels. You are looking at a different image's pixels. A quick scaling of your image. The scaling is done for good performance not the best image quality. At some zoom percentages the scaling look quite poor. Only judge your image quality when you are viewing your image actual pixels (Zoom 100%).
So there is no way that I can see image without this pixelization? For example I want to work with colorgrading and of course I can't look at just small area of my image with 90% zoom
Ok, I found solution. Just turned OpenGL in settings