Better yet they wouldn't even need to be madic users

on one hand it could be accidental where everyone is looking for any kind of magic even artificers but it's just very bad luck that magically ground flour is a new craze so the docks and warehouses that keep exploding haven't been storing the flour right, there's enough left over magic in the flour to make it disperse in the air sometimes then some old fashioned places are still using lanterns for light, police and gangs alike are on a man hunt

or you could have a pretty basic setup of a fine finely ground powder inside of an empty egg with some kind of rune that let's out a small fireball when destroyed painted on the side, everyone thinks this low lever magic user is some grand wizard for transmogrifying eggs into explosions, on top of that I wonder if thermite can be set off in a powder explosion kind of way