Is this map projection making Russia look small an artifact of the projection (i.e. we expand the land in the north more than the south in this projection in general) or an optical illusion?

Russia looks small flipped on its head and I can't quite figure out why.

> (i.e. we expand the land in the north more than the south

Yes. This is a consequence of the fact that the "land in the north" is, on average, further north (of the Equator) than the "land in the south" is south (of the Equator).

The southernmost point on the South American mainland, per Wikipedia, is Cape Froward, Chile, at about 54°S. For perspective, some cities between 53°N and 54°N include Edmonton, Alberta, Canada; Hamburg, Germany; and Dublin, Ireland. Similarly, the capital of New Zealand is about in line with the capital of Albania, and the capital of South Africa is about in line with the capital of Qatar.

It does seem to look visually less squished if I flip the image over, so beyond the projection, I would also say yes to optical illusion to some extent: https://i.imgur.com/JPIuvYl.jpeg

I don't think Russia looks small on this map, it's just not as blown-out as on Mercator maps. When I was growing up in Russia, the map I had in my room was a similar projection -- except with the North up, of course -- and Russia was about the same size on it.