On September 24, Blizzard announced that the WoW Forever beta was taken offline for maintenance while a new build was deployed.
What Blizzard confirmed
The maintenance announcement said the beta would be down for at least a couple of hours and that a full change log and updated known-issues post would follow. The development notes and known-issues update were subsequently published the same evening.
This type of maintenance notice is useful when tracking the beta chronologically: the maintenance event, the build notes and the known-issues list are separate sources and should not be treated as the same announcement.