I’m not sure if it’s based on any actual accepted term in art circles, but it is essentially a nonexistant concept that has been made up out of nothing. A bunch of pathetic manbabies are upset that the new thundercats cartoon coming out is both goofily drawn and comedic in tone. So they have come up with this term “calarts” and are essentially declaring that every single cartoon right now is using the exact same art style and is homogenizing and destroying western animation. Stuff like teen titans go, gumball, ok-ko, star vs the forces of evil, steven universe, etc etc etc. These people claim all these shows and more look the same, even when they very much don’t. For some reason, in these past few years, people can’t just call a show bad and move on. Everything has to be part of some grand conspiracy to destroy culture. So Thundercats Roar can’t just be an ugly cartoon that they don’t personally care for, it has to be a new pin on the conspiracy-board of how evil leftists are destroying cartoons. I find this doubly-hilarious because I recall last year several folks calling this a golden age of good western animation just last year. And now with a single cartoon we’ve gone from “one of the best times for animation in the west” to “we are now literally in the holocaust for animation”.