Cant be ad revenue, it would be stupid. But going into a pot Spotify style is also evil and not fair.
https://support.google.com/youtube/answer/6306276?hl=en#zipp...
It's pretty vague, but my reading of this is that it's paid out of a single pool based on the watch time of all YouTube Premium Members. So e.g. if you only watch one video a month, that creator doesn't get all of your money.
If so, maybe I should seek out worthy YouTubers to donate to be leaving it running in the background.