There are two versions of WebGL: WebGL1 and WebGL2. SketchUp Free has been upgraded to take advantage of WebGL2 features. This is unfortunate, because as a cloud app, users cannot keep an old version that works for their hardware.
WebGL2 is new and I suppose we will initially see the same procedure as with the first WebGL, that browsers manufacturers rigorously blacklist devices they think may not run well. Check out in about:flags, whether you can force-enable WebGL2 and whether it actually works for your hardware.