I've been able to determine that most of the display issues I've been experiencing are due primarily to the video card I was using. I've been in the process of rebuilding my primary PC this week, so I was using an alternate that I have. The two PCs are identically configured, with the exception that the alternate is used mostly for business and doesn't have a great video card installed. It's a Radeon HD 8570, which isn't a great card. I've been experiencing a great deal of lag and very poor graphics performance with my Stadia settings set to Best Visual Quality. Last night, I turned it down to the Balanced setting, and it was better, but not what I was hoping for. So, probably the video card. However, Google hasn't given us required specs for video cards. This is what Google says you need to run Stadia on Chrome:
Note that there's nothing about video card capabilities or specs. These specs seem to mesh with what I think most of us think about Stadia - that it's largely hardware independent since the games are running on Google's servers and we're just seeing display output.
This morning, I finished with the primary computer, which doesn't have the most current card installed, either, but it's a GeForce GTX 970 that I play a lot of games with at very acceptable settings. Well, what do you know? Playing Tomb Raider on Stadia on THIS card at the "Best Visual Quality" setting results in a smooth and largely fuzz-free playing experience. It's like night and day.
So Google, I think you need to make this clear, that the video card we have installed in our PCs needs to meet some minimum spec in order to have an acceptable gameplay experience.
I'm running Stadia on balanced/1080p on my Intel i7-4770R with Intel Graphics. There is no video card in my PC and I don't have any issues.