Cosmic Flux Available as Currency Reward from Great Vault in Patch 9.2

wowhead.com:

In Patch 9.2, Cosmic Flux has been added to the list of backup rewards from the Great Vault, allowing players to choose this option if they don't like any of their weekly gear choices.

Cosmic Flux will be the main new currency in Patch 9.2 that can be acquired from most activities in World of Warcraft. Just by playing the game and participating in Season 3 activities, you should get a decent amount of Cosmic Flux that you can use to upgrade your Legendary to Rank 7 (Item Level 291), and craft Tier Pieces at the Creation Catalyst (when it opens on Week 8 of the Patch). For more information on Cosmic Flux acquisition, click here!. Cosmic Flux Acquisition

Throughout Shadowlands, 3 Attendant's Token of Merits can be chosen if you don't like any of the choices in your Great Vault. In Patch 9.1, you can currently trade these in for Stygia, Anima, Soul Ash, Cataloged Research or Korthite Crystal. Patch 9.2 adds the ability to purchase Cosmic Flux Parcel from the vendor. With all 3 Attendant's Token of Merit, this will get you 1,500 Cosmic Flux.