Is it common knowledge that Dala Prisma is an actual prism?

It's a screen artefact, related to *Moiré patterns*. In this case, the distances between the thin lines, which are heavily antialiased because the lines are so thin and at a slight angle, interfere with the *coloring* of that same antialiasing.

That is: pixels to the left of a 'black' pixel are tinted slightly red, pixels to the right of a 'black' pixel are ever so slightly tinted blue. This makes it look as if the black pixel in the center smears out into the RGB pixel triples to its left and right, but only by one 1/3rd of its width, rather than an "entire gray pixel".

Fortunately, giving it a scientific explanation does not take away its incidental beauty.