Why does the image quality deteriorate with a strong zoom, although the quality is excellent in Google?

Question

Unity

I insert a picture of a map of Russia, the dimensions are huge, somewhere around 10k, I tried 5k, but the same thing
In the first picture, the image is enlarged to the maximum, and the quality is not lost, but in the unity, the quality is terrible.
The picture is exported to the unit as a sprite, there I tried both on billinear, and on trillinear and on point no filter, but everything is the same, even the graphics settings were set to max and everything was the same, exported to PNG extension.