“You’ll find the full list of changes coming in Sim Update 12 in the release notes. Please also note that WASM on Xbox support is planned for Sim Update 12, but is not available to preview at this time. We will be working with our Marketplace partners who have WASM-dependent Xbox content to verify correct functionality.”
https://forums.flightsimulator.com/t/read-first-welcome-to-the-sim-update-12-beta/562534