The “BluRay” tag indicates that the file was sourced from a retail Blu-ray disc, not a webrip or telesync. This suggests relatively high quality (assuming a good encode). However, the use of “BluRay” does imply official authorization—it only describes the source medium.
The tag typically refers to the release group or the website that ripped and distributed the file. -Movies4u.Bid-.Fight.Club.1999.720p.HEVC.BluRay...