[quietvoid]

Kodi has done nothing to enable that as far as I'm aware, thus I suspect it's due to an under the hood ffmpeg change that slipped in without any of us realising when ffmpeg has been updated.

I can't double post on the other thread so I'll put some info here.
FFmpeg hasn't received patches to add the new Matroska spec support.
Plex has updated their LICENSE file to mention the latest ffmpeg source update: https://downloads.plex.tv/ffmpeg-source/...dbb.tar.gz

In there, the code for the new Matroska BlockAdditionMapping elements seems to be present. You can search for "mkv_parse_block_addition_mappings", which indicates the dvvc and dvcc support was added for parsing Dolby Vision off of Matroska files.

So the code is definitely available to make changes to ffmpeg, it just hasn't been contributed back.
I can't really help with regards to that, but hopefully this reaches someone who can.