It's not white, it's the blueish grey #E1E8ED. You need a better monitor :)
And this is despite that fact that the actual "font color" is #14171A with excellent contrast: https://contrast-ratio.com/#%2314171A-on-white
But these bizarre characters don't respond the text color and thus utterly unpredictable in their legibility.
> these bizarre characters
At least on Twitter.com, they're not characters, they're SVG images.
At first, I was thinking that I could see the difference quite clearly between the two colors and I had no clue what you were talking about. Then I hit the "swap colors" button and happened to notice that there was a bunch of text on the left side that I hadn't even seen...