>>718395950
Yes, it's just the original data from the disc stuffed into the new container (like .mkv) "as is" so you could play it in any software player. It can be from 4k or 1080p source, or not even the blu-ray, then it's just Remux.
Since it's not re-encoded, the resolution of Remux video is the original resolution, so if your video is 4k than it was made from UHD blu-ray.