Ok I thought it blocked and muted the npub completely.. I understand some may slip thru when they shitpost nonstop and we are on the same relays..
Discussion
It should mute them completely, for you. It's just that on Nostr that's all "mute" means. The notes from that npub are still there on the relays, your client just shouldn't display them to you anymore. Anyone else who hasn't muted that npub will still see them, though.