Previously, if a blocked user searched for your name, your profile would not appear. After you unblock them:
Based on Facebook’s official help documentation, user experience reports, and platform behavior analysis spanning several years, does facebook notify when you unblock someone
When you decide to unblock a user, several things happen immediately, but none of them involve a direct notification to the other person: Previously, if a blocked user searched for your
Although there is no system-generated alert, User B might indirectly deduce they have been unblocked through observable changes: user experience reports