Mean Girls premiered in Washington, DC in late 2017 and began on Broadway in the spring of 2018. I've heard/read in multiple interviews that The Prom had a 29-hour lab four years before it was on Broadway (previews started October 2018) and had it's first full production at the Alliance Theater in Atlanta in summer 2016. I've seen bits of the choreography from that Atlanta production of The Prom and it doesn't look very different from the Broadway choreography. So perhaps there was recreated staging from The Prom in Mean Girls. (I haven't seen Mean Girls, so I can't compare.)
Bit of trivia: I understand some of the ensemble from the Atlanta production of The Prom ended up in the ensemble of Mean Girls.