When the status of a task with a parent gets updated, I get two notifications:
user changed the status of T123: XXX from "Open" to "Needs info"
user changed the status of T123: XXX, a subtasktask of T456: YYY, from "Open" to "Needs info"
I like the word "subtasktask", but I think it's a typo.
Also I like the idea of the second notification but it makes the first one redundant if I'm subscribed to both. If that makes sense, I can create another task for that.