Originally Posted by Blizzard
(Blue Tracker / Official Forums)
‘We recently developed a hotfix that restricts frequent layer-hopping, without impacting those who simply wish to play with their friends. Following realm restarts earlier today, this hotfix is now live in all realms in the Americas and Oceania region.
Now, each time a player moves to a new layer, there will be an increasing amount of time before that player can move to another layer. If a player moves between layers multiple times over a short timeframe, the cooldown can increase to a duration of several minutes (or longer) before they can change layers again. The cooldown will then decrease over time for players who don’t change layers.
This hotfix will become active in other regions following their next realm restarts.