The artist drew this costume twice (post #9986754) but I can't find it elsewhere so presumably this is their original design, though I feel it's still likely from some song or event that I just haven't found.

Looks like this design is from official merch of the Hatsune Miku x Rascal collaboration, from 2021.

This is the official art drawn by teshima nari. Couldn't find a better version of the art unfortunately.