When I try it on your tileset I can definitely see a quality improvement, at least on desktop.
It looks like it might just not be rendering to a high enough resolution on that mobile screen, which I think is what that setting is supposed to fix, based on the explanation here:
Thank you Omar. I tried that method in your link and it works!
Although it may not be a good practice to setting “viewer.resolutionScale=window.devicePixelRatio”, it is still a practical approach to achieve high quality with some sacrifice of performance.