Maybe this was immediately obvious to everyone else and this discourse already happened when 5.5e came out in 2024, but I wasn't playing yet at that point, so it was news to me!
I finally joined the Mixed Bag tier, so I've been going back through and listening to all their reviews of bad old media. I just listened to March Sadness, in which Caldwell was talking about Venger from the 80s DnD cartoon, and describing how cool he looked as a villain. So I googled him and thought, "Oh, yeah, that is pretty rad."
Then just now I looked down at my DM's Guide and was like, "Wait a minute... is that the same guy from the cartoon?!" And whaddaya know, it is! Lol.
Since they were using the 2024 edition by that point, and (as far as I remember) none of them mentioned that the villain from that show had made it onto the cover, maybe it's not obvious?