:
If you remember the user’s handle:
No. YouTube does not send notifications when you block or unblock someone. The only way they might realize they were unblocked is if they notice they are suddenly able to comment on your videos again. how to unblock users on youtube
A pop-up window will ask, "Unblock user? They will be able to comment on your videos." Click Unblock again to confirm. : If you remember the user’s handle: No