Unpaywall records have a new property - oa_locations_embargoed. From the docs:
This list includes locations that we expect to be available in the future based on information like license metadata and journals' delayed OA policies. They do not affect the resource's oa_status and cannot be the best_oa_location or first_oa_location.
It may not be new to you; we actually added it back on 2021-01-07. We haven't been consistent about announcing new fields when we're still working on their behavior. Sorry about that. They shouldn't cause problems in most use cases, but in the future we'll make sure to announce them here and update the change notes.
Richard