wasn’t there the Batman Ninja movie? I never saw it,

You just described pretty much everyone's experience with Batman Ninja (and, yes, it was literally just called Batman Ninja). That said, no, Eri Osada did key animation on other series, perhaps most notably Seikon No Qwaser (although they did 2nd key animation, it's still key animation). So, if a central focus on this Suicide Squad show is a breastmilk drinking fetish, I'd say we're in good hands. Otherwise...meh.