YouTube and copyright

I have the opposite curiosity... would one run into sanctions? I doubt SIAE would recognize anything for you anyway

The company or the private rights holder can claim their rights and the protected audio tracks are deleted. Practically, if you are the composer and have registered that track with SIAE, you can use a YouTube form to claim your rights over the audio track of a video that has used your song without having the rights to it. YouTube opens a dispute with the author of the video and cancels the audio track or blocks the video. In serious cases, the YouTube account that committed the offense is banned; in other cases, the video is blocked or the audio track is deleted, but nothing else happens. Practically, you cannot seek recourse against either YouTube or the account holder, also because it should be in your interest not to circulate tracks reserved for special events that you do not want being circulated before the event (I am giving the example of a title track for an upcoming film that comes out before the film). In the event, however, that it is a track available for purchase, you can claim the right aimed at requesting cancellation. It seems to me that this was the answer you were looking for.

You have touched on many topics, but specifically in my case, one of my tracks was published by others without consulting me. Not that I mind because it is very "clicked" [popular], so, since the music is mine (even registered), I was interested in understanding if I can squeeze some money out of someone.... and how....

As far as I know, you can't. Also because YouTube offers a service, but it seems to me that it only gives rewards after one million views (200 euros), at least that's what some of my classmates told me. Starting a war for four cents seems completely useless to me. If I were you, I would be happy about it because it could provide free advertising, but everyone decides how they want to act. If you want to do things officially, you should consult a lawyer expert in internet crimes (there aren't many) and hear what they advise you.

... imagine if SIAE went asking for royalties

here is a link regarding the SIAE

https://online.siae.it/assistenza/GestioneTickets.aspx?id=9