Blocking is supposed to stop someone from reaching you. Until now, though, it only stopped direct messages — which meant a person you'd blocked could still apply to your listing, ask a question on it, invite you to their party, or be added to your roster.
That's fixed. A block now stops all of those too, in both directions: whether you blocked them or they blocked you, the interaction simply won't go through. And we never tell the other person that a block exists.
You don't need to do anything — your existing blocks now cover these interactions automatically.