Thanks for the tips! Unfortunately the banding still appears in all the exported renders using H264. The PNG and EXR stills themselves look good with the 16 bit or 32 bit color depth, it is only when they are exported as videos. Found this article on banding and found that Apple ProRes 422 codec plus a Premiere noise grain filter yielded the best results with the PNG 16 bit files. Hope the info helps someone else!
