Please update with the correct steps the Release Note 11.12.x https://help.jiraalign.com/hc/en-us/articles/37792768879252-Release-notes-for-11-12-X  on section "Team hierarchy navigation menu enabled for all" where is reported the following:

"The Teams menu will be enabled by default for all environments with this release. To temporarily disable this menu, navigate to the tab and select Yes in the Enable Team Hierarchy dropdown."

The above statement is not clear to understand how to enable/disable the new feature

The correct steps are: 

To disable/enable this experience "Team hierarchy navigation menu enabled for all" go to the  Settings > Platform > General tab and toggling the Enable Team Hierarchy option to 'Yes' or 'No'. 'No' means to have back the old navigation.

This approach can help to perform the necessary tests and prepare the users for these new changes meanwhile the Atlassian Content Design team will be updating articles and guides with team hierarchy navigation information as reported in the release notes 11.12.x.