I only see it on low-dpi displays. Not visible on mobile or Macs.
Lol…?
Nothing with a high DPI (“Retina” in Apple parlance) display showed it in my testing, which includes most mobile devices made within the last 10 years and most Apple products.
While high DPI displays are becoming more common for Windows-based PCs and laptops, many still ship with low DPI displays. I have one hooked up to my gaming PC, so I was able to verify the existence of the Single Blue Pixel there.