Obviously these circles were made in the 2D engine, scratch. But, look at them closely enough, and they kind of look like they are spinning around in a whirlpool way. They kind of look 3D yet they are 2D. I like to call this the "Sonic Mania effect."
If you didn't know, Sonic Mania is a 2D game, but sometimes you can find objects that look 3D in the 2D world. An example is the Press Garden Zone platforms that make your character spin around. It seems like your character is spinning in 3D but it's actually just different sprites in different places (in 2D). Weird yet neat!
