This morning we merged the first commits of the farmOS 4.x branch (Start the official farmOS 4.x branch by mstenta · Pull Request #949 · farmOS/farmOS · GitHub), which means the 4.x branch is officially open! 
It also means that 4.x is now the default branch, and all new changes must be made against it, including new features and bug fixes. Bug fixes will be backported to 3.x until the first “stable” release of 4.x is made. At that point, 3.x will no longer be supported, and everyone will be encouraged to upgrade to 4.x.
Expect a lot of changes on 4.x over the next weeks/months, as we focus on breaking changes (including the upgrade to Drupal 11) and new features. The meta tracking issue for farmOS 4.x development is here: https://www.drupal.org/project/farm/issues/3488918
There is no scheduled release date. Much of this work is happening on a volunteer basis, so it will be ready when it’s ready. If you have any breaking changes you would like to see happen in 4.x, now is the time to put together pull requests and submit them for consideration!
