Your quite welcome. My apologies I forgot to provide the link for Playa’s repo.
https://keybase.pub/playa/Pimax/Firmware/4k%20Series%20(P1)/
Sorry to hear the black bar is present even in older piplay?
The 999 firmware is said to improve ghosting iirc by making it a bit of motion blur? Haven’t tested it.
You may still want to try a support ticket. With it being 4k you may want to request @Doman.Chen . @PimaxQuorra can likely help with ticket.