It was later discovered that John Carter and the Giant of Mars was actually not written by Edgar Rice Burroughs, but was ghosted by a relative. A mere pulp mag like Amazing Stories having a Burroughs story was a hell of a get, since he was the best-selling writer of the entire 1920s.
What’s interesting is that the later Mars stories were written out of an early desire for “nerd nostalgia.” The stories had their heyday almost a couple decades earlier, and scifi as a field moved on to Stanley Weinbaum style truly alien-aliens. Burroughs returning to Barsoom at the request of Amazing Stories was “retro.”
It’s fascinating to imagine something being “retro” at that early date, but there we are. I could probably do an entire youtube vid around this (and I just might) but prior to the 1980s, nostalgia was only really a thing for old people and was not a cultural force. That changed in the 1980s (a decade mostly defined by 50s nostalgia), mostly because Western culture started to embrace the neoliberal consensus, the idea the kind of government and society we have now is the “end stage” and history was over, so they just started to sell you the past over and over again. This is also why 1960s style futurism started to vanish.