If New drives fail, can you replace your pool with the old drives?

I have a TrueNAS build that had 6 mirrored vdevs across 4TB Drives. I just recently upgraded 2 of the vdevs to 8TB drives, resilvering went just fine, everything worked like normal. Today one of the vdevs had both drives fail, and it seems like both are completely unresponsive. I still have the original 4tb drives that were in the system, and no changes have been made to the data since adding the drives. Is there a way to reinstall the old drives and save the pool?

I’m afraid not. Replacing the drives was a change.