The meme actually uses the exact same image as the wiki page about the tests. https://en.wikipedia.org/wiki/Ishihara_test
The number “74” should be clearly visible to viewers with normal color vision. Viewers with red-green color blindness will read it as “21”
So at least I’m seeing what I was supposed to see!
Yeah, the number is in green and the background circles are light brown to beige.