I say this not to discourage you, but what's being described here is far from an edge case. Providers have often up to ~90 days (when in network with the plan) to submit a claim. Then payers have time to process the claim and adjudicate it. If the claim is denied, providers have more time to appeal the claim, etc.
Again, this isn't intended to be discouraging at all. Just don't operate on the assumption that eligibility APIs showing out-of-date deductibles is normal and not an edge case!