Like many of the "retro" style mirrorless flat cameras, it is too tall for the proportions to be exactly right. The Nikon Zf is a clear example of this, find as I am of mine. The smaller center viewfinder Fujis (X-Txx) do a bit better, but are still a bit off.
In any compact manual 35mm film SLR, you can see how it's built around the basic needs of the film. It's a wide rectangle: film canister on one side, take up reel on the other, and between them the width of the shutter, with a little extra all around for the working parts. The mirror box sits in front of the film box, with the viewfinder on top. If it were any taller than it absolutely has to be, it would fail at being compact.
If you wanted to make a digital mirrorless with the same proportions, you would have to sacrifice rear screen size. So far, it doesn't look like manufacturers are willing to do that.