Support for clearly seeing in Maniphest which versions/project branches a task has been fixed in.
We for example have 3 releases to support, say 1.0, 2.0 and 3.0. A bug found in 1.0 might need to be fixed in 2.0 and 3.0 as well.
Currently it seems that to manage that, one could create subtasks for the other versions and handle them like the main task was fixed. This has a bunch of busy work: create the subtasks, change the Project for those subtasks, copypaste main task's title to the subtasks and possibly prepend it with the version number (so you won't have 3 tasks with the same name and can identify better which version that subtask is for). This could be alleviated by creating some sort of task copy tool using conduit or skills permitting, adding a clone button to Maniphest which does this.
While it's nice to see the multiple clone tasks in "arc tasks" so you see where you still need to push the fixes, the clones do pollute the task space.
Nicer solution would be for Phabricator to record and show in Maniphest which (pre-designated) project branches a related commit/arc land has appeared in.