Remux is not a community, it's a tag that pirate release groups uses to indicate that a release contains exact copies of the original video and audio streams present on the disc.

GP is correct that files with purely additive changes (like additional audio tracks) to remuxes are called hybrid remuxes.

ETA: To the author's credit, this is convention rather than a hard rule. I checked my usual sources and found the exact 89gb 4k Arrow remux the author mentions in the closing paragraph and it is indeed labelled 'remux' only. The uploader did make a note of this though: "Unfortunately, as Arrow had to pull the Italian dub due to rightsholders demands, I had to sync it from the 2017 Kino Lorber disc."

>Remux is not a community, it's a tag that pirate release groups uses to indicate that a release contains exact copies of the original video and audio streams present on the disc.

There is a community insofar as there is a relatively small group of people who sink their time into producing high quality remuxes, and this group talks to each other (on IRC and elsewhere).

>GP is correct that files with purely additive changes (like additional audio tracks) to remuxes are called hybrid remuxes.

As I corrected on a child comment to the GP, this is not correct. It is not convention either. A hybrid remux has a stream which is a hybrid of two or more sources. Simply combining tracks from different sources isn't a hybrid remux, it's just baseline good practice.