A search turned up https://www.toptierwaifu.com/products/kurumi-maid-decal, but it's not clear if that's the original source. The website owner does not claim to be an artist, nor do they attribute it to an artist. Looking at other images there, there seems to be a consistent style, like they are produced by the same person, so at the very least he doesn't appear to be lifting from image boards or Pixiv willy-nilly.