Fun House Glass
I posted my own thread about this a long time ago. I don't believe our windshields are a particularly quality piece of glass. Sitting in the driver's seat at a traffic light, I amuse myself by looking to my right, through the passenger-side portion of the windshield, and moving my head side-to-side to watch the way the scenery warps. It's the oblique angle that points out the flaws: Looking straight ahead, all appears fine . . . which is why I'm not going to have the windshield replaced.
The flaws in my glass seem like a series of vertical lines, almost like what you'd find on an accordion. If I focus on a fixed object outside the car while seated inside, swaying back and forth makes that object look like a cork bobbing on a ripply lake.
Our side glass is good stuff, made by Pilkington. You can find their logo on it if you go look. The windshield, by contrast, appears to be sourced from China.