Shadow Users were not initially evil
In the film, the conventional magic users, teachers and students alike, treat upside down magic users with immense racism and disdain, due to them not being normal. Shadow Magic is treated as being bad, but it had to be a normal magic type at some point. It almost makes one wonder if centuries ago Sage Academy treated Shadow Magic users with even more hate and disdain, to the point that it drove Shadow Magic users into being evil. The speech possessed Reina gives to the Academy during the finale seems to hint them having immense hatred towards the Academy. Upside-Down Magic is a metaphor for neurodiversity acceptance.
Throughout the film, there are parallels between UDMs and neurodivergents, specifically people with ADHD and autism. Skriff, Elliott, and Nory are atypical-looking, fitting the stereotypical autistic image, Andres being quiet and using assistive technology in the form of his weighted backpack. Pepper is passable as “normal,” just like people with ADHD or high-functioning on the autism spectrum. UDM is a negative acronym, just like ADHD, and “normal” students treat it as an insult, just like how some neurotypical people use the word "autistic." Reina’s atypical flaring reveals UDM is a spectrum, just like autism, with Reina becoming a savant at flaring, but also very vulnerable to criticism. UDMs are segregated, just like special education students. UDMs are forced to suppress their powers, just as neurodivergents are pushed to assimilate into neurotypical society. The climax of the film is about UDM being a different rather than inferior form of magic, recalling how ADHD and autism have benefits, not just being mental illnesses. In the end, UDMs are integrated with the other students, their powers embraced, just as neurodivergents hope to be included rather than assimilated in mainstream society. All Flickers could have omnidirectional telekinesis if they worked at it.
At the end of the movie we see Pepper sharing out gum telekinetically to everyone at the table. She's pushing stuff not just straight out away from her but *across* her path/line-of-sight. At the same time, at that. Andres "feels" his magic as a constant upward pull, most likely focused on his shoulders.
The risks of growing kids carrying too-heavy backpacks are well-known in
Real Life. Andres wears his 24/7 to hold himself to the ground; now consider that if the magic acted as a pushing force from the ground focused on his feet while he's standing and his tailbone while sitting the effective weight of the pack on his spine would be more than doubled and if his magic first manifested at the age Nory's did he'd have reached the point of a noticeable physical deformity from its' constant strain on his back (assuming weighted boots weren't offered as a better solution). Yet here he is with the backpack and the build and posture of a Disney kid on the first stage of the Teen Idol process. The magic not only has to be counterweighing the backpack, but doing so in such a way that a weighted backpack is the optimum counterweight to it.