In the context of a duress defense, is the government's untimely disclosure of exculpatory evidence material under Brady v. Maryland?

QUESTION PRESENTED In the context of a duress defense, is the government's untimely disclosure of exculpatory evidence that (1) corroborates the defendants' wellgrounded fear of harm and lack of reasonable opportunity to escape, while also (2) impeaching contrary evidence, material under Brady v. Maryland, 373 US. 83 (1963), or is it irrelevant?