What the signature actually asserts
It is not a warranty that nothing is wrong. It is a statement that a competent person read this work, within this scope, on this date, and considered it fit for the stated purpose.
That distinction protects everybody. The reviewer is accountable for the reading they did, not for defects outside the agreed scope, and the organisation gets an artefact it can point at instead of a memory of a meeting.
It follows that the scope must be written before the review, not reconstructed afterwards. A signature that says approved means nothing; one that says reviewed for factual accuracy and regulatory claims in the pricing section means something.