mod-patron needs to map possible returned statuses properly or else this could cause failure. In the case of requests, mod-patron is missing the "Open - Awaiting delivery" status in its "hold" schema. This status is defined in mod-circulation as a possible request status. All "Open" status requests are retrieved by mod-patron. I believe that adding entries to an enum does not count as a breaking change, even though it clearly breaks this implementation, which is likely how it was added without impacting this module.
Anyway, this is yet another thing that we need to manually monitor in order to not break the implementation. I think request delivery is likely rare at this point (Goldenrod), so it is not surprising that failure has not been observed.