https://github.com/TeamPiped/Piped
https://piped.kavin.rocks/
https://piped-material.xn--17b.net/
I suspect it might be supplying specific filters (e.g., "intitle", mentioned elsewhere in this thread) to YouTube's query engine.
https://github.com/TeamPiped/Piped/blob/860ca92a4d49a85a3781...
That looks strongly like a simple pass-through.
https://github.com/TeamPiped/Piped
https://piped.kavin.rocks/
https://piped-material.xn--17b.net/