I cannot find a name for this song other than "Test Music" but I am suspicious that this is what the song is actually called. Similarly, I cannot 100% confirm if Kurihara Masaki is the author, but he has composed other songs for the show.
While the current YouTube channels do not address this, an archived channel page provides a link to the Twitter profile: https://web.archive.org/web/20190130160721/https://www.youtube.com/channel/UCZ6VvYuzEdiFeoBh8gckCeg
Based on what I documented back when people actively contributed to this fad (see here: https://twitter.com/FinnOtaku/status/1732575488067989956), this is the earliest upload I'm aware of. Thus I've tagged this work with "the cause of it all".