I have thought of this as knowing _about_ things, as opposed to knowing things, and not having the self-awareness to be able to differentiate between the two.

I've seen this most notably in a former coworker who enjoyed watching YouTube videos (especially when the rest of the team was hard at work, but that was another point of contention entirely). He thought himself very knowledgeable on various topics because he could readily regurgitate talking points, but if you asked him about second-order effects, or implicit simplifying assumptions, or how X from the video would be different if Y and Z were different, it was obvious how surface-level his "understanding" was.