It is out of date, or currently irrelevant.
In order to facilitate the demand for phantom membrane; and to please those who do, and no not support phantoms; they will be enabled between the hours of 10:45PM and 6:45AM on the server. Phantoms begin to spawn after it has been an hour since your last sleep, this may be checked in Statistics under Time Since Last Rest.
In addition, the multiplayer sleep datapack has been updated to the latest version and now requires that 50% of the players on the server be sleeping before it passes the night. This is to alleviate some of the issues when only one player is required to sleep. A pop-up also appears now to warn other players when another is sleeping.
Phantoms slowly increase their spawn rate the longer since your last rest. They will spawn in groups of 1-3. It must be nighttime or a thunderstorm and players must be above sea level (y64). Read more about phantoms here.
