(HTML5 on mobile) bitmaps do not look smooth when allowHighDPI is false
That looks like an artifact of resizing.
Suppose your assets are meant for super dense screens and each number bitmap is 256 by 265 pixels.
When you try printing in without highdpi you try to print them in 64x64. That resizing kills your quality.
Same can happen the other way arround, if your assets are 32x32 and you try to put them in highdpi that makes them look 256x256 you will have blurry rescaled assets.
Also, keep in mind that if you are testing on chrome using the device simulator thingy, that adds another layer of scale that might look even uglier.