I've procured MA from many different sources - Ace Hardware, Leslie's, Patio Pools, etc, and it is only the Leslie's brand that I find being a strong yellow color. I know MA can have by-product from production in it that can make it a pale, straw yellow but this stuff from Leslie's is a VIBRANT yellow. When I did lab work with reagent grade HCl (back in my working days), it was always clear.

Do they dye it for "safety" or is it truly contaminated with something?

It works just fine at lowering the pH and is always on the money in terms of pH change as calculated. Just wondering what they use to make it so yellow.