With the announcement of the release date for Patch 11.0.5, Blizzard has revealed that the secrets coming with the 20th Anniversary event, the Guest Relations Questline, will be available during the second week of the patch, starting October 28th. Additional secrets will be available on November 4th.
20th Anniversary Event Guide
What are the Guest Relations?
During the 20th Anniversary event players will be able to interact with visitors to find riddles and clues to uncover a mystery. This is a sequel to the popular Secrets of Azeroth event that happened during Dragonflight.
The rewards for the event are currently unknown.
Blue Post
Often a thankless job, guest relations has a new volunteer, Alyx, stepping into the role with the lofty hopes of doing a better job than their predecessor. As visitors pour into the celebration, Alyx is under pressure and could use a little help making it an event to remember. Thankfully, they have found a secret-sleuthing tuskarr family who have become the perfect helpers in getting players up to speed with the tools of the secrets trade.
Assist Alyx each week with resolving new guest mysteries by using your new secret-finding skills, and be on the lookout for stolen celebration goods. Follow the rumors and solve the mystery— if you can. We’re counting on you, secret finders.
Players can begin working on the initial secrets beginning on October 28 with additional secrets opening up on November 4.
Read more on wowhead.com