Someone - Does Facebook Notify When You Unblock

The person you've blocked won't receive a notification about the block, but they may realize they've been blocked if they try to visit your profile or interact with you.

The ability to see a profile or send a request is a passive discovery , not an active notification. Facebook does not proactively message User B stating, “You have been unblocked by User A.” does facebook notify when you unblock someone

You can unblock someone safely knowing that Facebook will not "tattle" on you. They will only know if they actively look for your profile or try to contact you. The person you've blocked won't receive a notification