"cartridges found at the scene were marked with pro-trans and anti-fascist slogans"

It is wrong to say that.

They were marked with Antifa slogans, and Antifa is _extremely_ fascist, using violence to demand censorship and submission to their ideology.

The right way to put it would be like "cartridges found at the scene were marked with pro-trans and slogans from the overtly fascist group which calls itself Antifa"