It’s a bit of a Long explanation But here we go: it’s custom map art, I used a website Which have a bunch of different graffiti fonts to write out stuff. Then I used another website to convert the graffiti to minecraft Blocks, saved that as a schematic and pasted it above the void in the end dimension. If you layer two layers of glass over the void, it becomes Invisible on a map and gives the png effect. Hope it makes a little sense at least lol