Fake nostalgy?:

1. Old monitors rendered every frame line by line.
2. Slow internet connections loaded pictures like a slow printer, in little horizontal chunks appearing one by one.
3. Restricted color palettes in these days made all gradients have noticeable steps between colors, so maybe omitting some space between them made them look less borked, since your mind draw the transitional parts for you.

Idk, but this vaporwavy style is rooted in recreating or faking 80-90s visuals.