There are blurry gameObject cube icons on hierarchy and inspector. I tested 2019.4 and 2020.1. I don’t have any idea about how to fix this. Please Help.
You probably set the resolution of the default icons lower. (It happened to me before) I would search through the asset folder to find the sprite and change the import settings.
I had the same issue, Texture Quality settings caused my blurry icons.
Project Settings > Quality > Texture Quality - Set to full res and blurry icons went away.