The labels "Subject:" and "Message:" are too close to their respective text boxes, and there label for the consent checkbox doesn't align with the checkbox itself. The problem is also present in the upload dialog.
That is indeed the cause. Specifically, the feedback dialog puts a <p> element into the label, and I didn't expect block elements to appear inside it…
Unfortunately it doesn't seem like I can just blame it for the problem, because a similar pattern exists elsewhere, e.g. the upload dialog: