This is the latest official information. I hope it answers your question.

https://eu.finalfantasyxiv.com/lodes...6b1e0ba1d3c241

Regarding Changes in Congested/Preferred Worlds (Nov. 28)

After implementing World population balancing incentives, we have confirmed a shift in the number of active players in each World.
Due to the creation of new characters by new players and use of the World transfer service, the status of preferred and congested Worlds has changed.

We thank you for your consideration and understanding as we continue our World population balancing incentives.

Based upon the current population, we are changing the status of each of the following Worlds as of today.
We will continue to observe the number of players logged in and change the status of Worlds periodically in order to balance the population among Worlds.