Marvel fanboys/girls laid into Cameron Saturday on word that his 2009 behemoth of a flick had once again climbed to the top of the charts globally upon a re-release this weekend in Chinese markets, putting its new haul at just over $2.8B against 'Endgame's' $2.797B.

China's Film Bureau struck a deal that allowed for 'Avatar' to be re-released in theaters, seeing how they're testing re-opening cineplexes ... but are short on new material. Since 'Avatar' is an all-time great among viewers there, they greenlit its revival on the big screen.

Marvel was gracious in defeat, tweeting ... "Congratulations to @JimCameron, @JonLandau, and ALL of Na'vi Nation for reclaiming the box office crown! We love you 3000." Cameron responded with a blue heart emoji, y'know ... 'cause of the blue forest people.

While the studio is bowing down ... fans aren't. Many are pointing out 'Avatar' appears to be gaming the system with yet another re-release more than a decade later, and seemingly juking the stats in its favor. Yes, the movie has had a handful of re-releases over the years, including a significant one right after its OG one-month theatrical run in late 2009.

Here's the thing ... if 'Avatar' "cheated," so did 'Endgame' to get its huge numbers. That movie was in theaters for a whopping 20 weeks or so, which comes out to about how many months 'Avatar' has been left in theaters total on re-releases (give or take a couple months).