The fact that we have another connection to the Battle Network era aside from that small easter egg in one of the Starforce games and the Operation Shooting Star crossover.... I WANT THIS TO HAPPEN!!!
My first thought was this was a Kobayashi Dragon Maid reference, but that can't be since this art dates about 15 years ago and Kobayashi Dragon Maid debuted in 2013, roughly 11 years ago)
However I am not fully up to score in all the lore: why are conscious mushrooms sympathetic to Marisa, when she collects them for purposes which they presumably would find nefarious ?
Not being accepted into art school is not necessarily proof of anything; any more than not being accepted by the Fine Art crowd of auctioneers and top buyers means you're crap.