Black Debanding Challenge

[DJ Bobo]

Hi guys
This capture (https://www.mediafire.com/file/yz0a3nuqd4fjz7s/test.mkv/file) has been driving me crazy.
I can't get rid of the banding in the black suit.
I tried f3kdb, f3kdb Neo and Gradfun3, and none seem to help.
So if anyone can tell me the magic parameters to get the black area perfectly smooth, please, be my guest!
Thanks

[Selur]

try libplacebo_Deband (http://www.avisynth.nl/index.php/Avslibplacebo) with high radius (like 40 and multiple iterations like 10), when aiming for high bit rate output you can probably keep the grain to zero.

[real.finder]

what about?
convertbits(16)
GradFun3plus(0.2)
neo_f3kdb(sample_mode=4)