I believe this is a new Kodi thing.
Whatever you are using to get the metadata and write the NFO is likely using the newer FFMPEG standard I think.
I’m no expert, but I disabled that in NFOs in Ember and the OSMC skin started reading everything okay again when I rescraped them.
If what you are experiencing is the same as what I experienced I don’t think it will go away until OSMC bumps to the next Kodi and the OSMC skin gets updated to go along with the new way.
Is it displaying the codecs with underscores and stuff?
See here: [TESTING] Vero V: Dolby Vision TV led support - #322 by Kontrarian
And here: [TESTING] Vero V: Dolby Vision TV led support - #327 by Kontrarian