Gaming Historian comes to mind. (Caveat: he's no longer doing YT full time, so the uploads are a lot less frequent.) Anyway, he started out as the kind of prototypical kid with Youtube videos, doing a pretty well with the history angle. But over time evolved into a serious documentarion doing top-notch work. Along the same line, DidYouKnowGaming went from an ok channel that repackaged pretty common trivia into interesting but almost click-bait videos, into now being an investigative journalist kinda thing, where they semi-regularly share previously unknown information about old or cancelled games. Still on the games side, Electric Playground has been going for like a quarter-century, since back when it had to be on cable TV instead of Youtube, and Victor Lucas still doesn't suck.
3Blue1brown and Ben Eater make great technical educational videos that, as far as I'm aware, haven't really degraded.
Thank you for sharing, I had no idea this was a setting! That makes it a lot easier to get the other links.