The mainstream response, if this site can be called "mainstream", is that the shoes were digitally altered to make it appear they were different:
https://www.sportskeeda.com/pop-culture/distinctly-weird-nashville-shooter-shoes-conspiracy-goes-viral-sparks-raging-debate-vans-designI love a conspiracy theory as much as the next guy, but let's take this apart:
Seven families have to agree to "give up" their loved one to a faked death, such that they all agree, and nobody lets it leak, that the loved one will disappear, never to be heard from again, and given some kind of false identity, because, well, they're not dead after all. (Pretty tough to do for nine-year-old kids.) It's all arranged in advance, at one school, and everyone else who was at that school is sworn to secrecy. They have visitations in which something (or
someone?) is substituted for the seven bodies. If they're closed coffins, they are weighted down with something. If they're opened coffins, well, you tell me. All of the police officers are in on it as well, ditto for the coroners who file fake reports. And as for the school, it is run by an evil cabal who agree to hire 33 teachers as part of a sinister numerology scheme. They'd been plotting this for a long time, and the "shooting" was just the denouement.
Or let's say the shootings did indeed take place. Someone "got to" this troubled young woman, and got her to agree to disappear forever after the shooting (if she was that troubled, that part actually might make some sense), that she was spirited away safely, and that the video with the police was staged, that TPTB got command of the school, staged an apprehension, but someone charged with making this video look believable, messed up and put another garish set of sneakers on the "assassin".
Does Occam's Razor apply here?