This website creates karaoke song versions of any YouTube video
If you’ve ever tried and failed to find your favorite song in a karaoke song book, you’ll have better luck on Youka, a free website
that creates karaoke songs out of any YouTube video. Youka, short for “YouTube to karaoke,”
isolates vocals from tracks and pulls lyrics from sites online.
Technologist Andy Baio, who first pointed out the app, notes that the service most likely uses Spleeter, an open-source AI tool that isolates vocals from songs.
The Verge
https://www.theverge.com/tldr/2020/2/19/21144452/youtube-youka-club-karaoke-lyrics
Youka – Youtube to Karaoke