That's actually an oxide layer of plastic that naturally forms on Kraft singles after the manufacturing process.

"cheese"

For that reason, alongside the important aspect of taste, I always recommend deli-style American. Kraft Deli Deluxe, or Land-o-Lakes, or any number of other brands.

Deli-style often comes in a brick, pre-sliced and offset for quickly peeling slices away from one another (like how restaurants do it). It’s firmer, due to a reduced milk content compared to the Kraft singles, and holds its shape better under heat while still being the perfect, melty sandwich cheese that American is. There’s a reason some of the best burger chains use deli-style American as their main cheese.

Especially because wax paper works fine

Maybe, but they last a lot longer in the fridge

I mean they used to. These days I definite prefer cheese to “cheese”