Why are sprites pixelated?

Question

Unity

I created 1000x1000 px images in fsh. in the unity itself, the size is 125x125 (and what is measured by the way? pixels?)
Imported into unity. I set the following parameters (I pulled it up to the maximum because the standard ones seemed weak, but in the end nothing noticeably changed):

that is, when displayed in developer mode, everything is more or less of normal quality,

but if the game mode is running (even after building), then this is how it is all displayed

for what?! why?
ps also tried to make the picture itself 125x125 px, but it only got worse (an example is the molecular physics laboratory).

Answer 1

(and what is measured by the way? pixels?)

And everything is measured there in Units, and in the picture you have 100 pixels per unit. But you still have a downscale problem, and if it is not a multiple of two, then there will be artifacts.