devtrackers.gg
It's not unofficial servers .... There rented servers from EA An respawn. There tournament servers you have to pay for. My clan has three separate servers where you can change almost all aspects of the BR and arenas. From how fast weapons reload and fire to what map and type of map you play.
Edit : someone sent me a link to show this is indeed a "custom" server .... Made up by a clearly very clever little group of people . I still stand by my comment you can run your own tournaments on your own terms. My explanation didn't sit right with some people ..we don't HAVE three servers. We use 3 on weekends that we are given access to. Via a tournament code