Having been on the "creative" side of several of these kinds of graphic design projects, with some fairly large clients, I can assert that it's likely that the

Having been on the "creative" side of several of these kinds of graphic design projects, with some fairly large clients, I can assert that it's likely that the agency who did the design signed something to the order of "indemnify and hold harmless" for any copyright infringement suits, and has insurance for that eventuality. That insurance is likely to get a lot more expensive unless Netflix and the agency can come to an amicable resolution with the OP.