In the description text for train deployments, like T271344, there is
Any open subtask(s) block the train from moving forward.This means no further deployments until the blockers are resolved.
there is a space missing between "forward." and "This". However, when I try to edit the task (eg https://phabricator.wikimedia.org/maniphest/task/edit/271344/) the description field is empty, which I suspect means that the text being shown is kept somewhere else (part of a form?).