It seems this is still attached because your parent component (as I’m seeing on the left side panel) is the “Textarea”. So, if this element “Container” is part of an instance, then the documentation persists, I assume. You can try to detach the instance (just do it for testing) and check in the layer “Container” if this persists.
If I detach the component “Text Area”, then the link is gone from “Container”. But the link does not seem to appear in the component description of “Text Area”, only for the “Container” (see picture).
Funny thing is, if I detach the component and then create a new component, from that one, the link will reappear in the new component.
Weird…it’s really funny because, as you said, the “Container” is not an instance.
But, overall, is this a problem for you? Also…have you tried checking this in an account that has the UI2? Because this problem may be specific of the UI3. Maybe?