Do you have with the person whose profile you're interested in?

When a user enables the "Lock Profile" feature, non-friends are restricted from: Viewing full-sized profile pictures or cover photos. Seeing any posts, photos, or stories on their timeline. Viewing most "About" information. Accessing their complete friend list.

Non-friends see a limited "locked" version of the profile that includes only a few details (like a thumbnail profile picture and basic bio info).