Seriously, what, exactly, is filmmaker David Ayer trying to prove and or what exactly is his obsession with Latinx culture? After “Bright” and “Suicide Squad,” two spectacularly unwatchable dips into the pool of tentpole filmmaking, the writer-director has apparently decided to go back to basics—and for Ayer, “back to basics” means loathsome, revolting Latinxploitation. Throughout his career, whether in gang tales like “Harsh Times,” copraganda films like “Street Kings” or “End Of Watch,” where casual racism is second nature to everyone, and even the superhero story “Suicide Squad,” the Champaign, Illinois native has shown a borderline prurient fascination with the Latinx underworld. Who appointed him the go-to guy for these often stereotype-laced stories (other than marrying, and then divorcing a Latinx woman), and how many actual Latinx filmmakers are being passed over for opportunities and attention in the meantime?