Bright isn't a group, it's just one of many words the anonymous name mode pulls.
Maybe , The fact all have them use Bright at start of there name , end of day this guys using cheat , name is not important . I even try to look for them on search and didnt find anything not sure how its can happen , not sure how the keep play
Ruxem is correct, this is someone using anonymous mode, where the game is assigning a random username (this is also why you can't find them). There's also a Streamer mode setting that will do the same to everyone else. The names the game assigns usually begin with "Bright" or "Any", but there may be more variations out there.
The best thing to do when you encounter someone you suspect is cheating, is to report them through the scoreboard.
So many report and the keep play. some got rank 1000
