Megalo Box is intentionally made in very low resolution, with thick, coarse hand-drawn line art and relatively dark colors, in order to mimic the old celluloid era picture style. The native resolution is only 405p, while the ending part is HD. We downscaled the source to 720p, only cleaned up some banding, as well as very sharp aliasing and ringing during Blu-ray production, and left everything else intact.
Obviously it's pointless to upscaled it with whatever fancy scalers here, and 720p is enough to keep all the details. For easy comparison, the screenshots of the rip below were upscaled to 1080p with Spline36.