To add details to my tasks, i use normal bullet-list items indented underneath the tasks items.
In normal notes, they are not shown in the references section on top of the day (what is fine). But on weekly notes they are of course shown (also fine).
When i now mark a weekly task as completed, it gets hidden from the day-view, but the bullet items remain visible.
I think either keep the completed task, or also hide indented items underneath it.