It is currently not possible to export an encrypted dataset with subdatasets using -R unless -w is also specified.
But a recent addition the the zfs code includes -U which will not preserve the encryption property. I see it here Add --no-preserve-encryption flag · openzfs/zfs@5dad945 · GitHub but not in version 2.4.3 yet, and probably not in 2.4.4
Question: When can we expect this flag to appear?