How youtube algorithm actually sorts/understands that what is a song and what is not a song

How youtube algorithm actually sorts/understands that what is a song and what is not a song

This question is kind of haunting me for few days that how youtube algo understands that a certain video is a song or not

Like by the youtube pop up feature I can see youtube over different apps like like I'm seeing gate smashers video and simultaneously using chatgpt

But when it's a song like I'm not talking about proper song channels and all like a random less subscriptioned channel posted a song/music kind of and if pop up youtube then it doesn't work

But yeah I've noticed that if you're hearing music on YouTube shorts then I can pop up the video and if a music/video which is less than 1 minute and not a short for that also I use the youtube pop up feature over different apps

Like a algorithm can just understand numbers, variables, audios etc but how it segregates between if a video is a song or not?

I'll grateful and appreciate if someone explains the process