I love Stadia. I got the founders and everything - but 1440p blurriness on Chrome is so ridiculous with no solution I can find that it's almost unforgivable. Take a look at this screenshot on the pause screen - it's so pixalated that it's almost like I'm looking at a 720p upscaled image.
Here's my speed based on http://www.google.com/url?sa=D&q=https%3A%2F%2Fprojectstream.google.com%2Fspeedtest for reference.
Well I don't play at 1440p but I tried multiple Windows machines and some had blurry dark spots.
Some it helped to forced VP9 with Stadia+ and some just started to work nicely with Chrome Canary.
So maybe Chrome Canary is worth a shot.