It was brought to my attention that the lock icon appearing next to the names of some categories could be giving the wrong impression.
The lock indicates that a category is accessible to the user but is not accessible to everyone. Access to some categories is based on either group membership or trust level. Access can mean the ability to read, reply, and/or make topics.
However, as far as I know, users who cannot access a category simply don’t see that category at all. Thus, any category with a lock that a user can see is something they can access, but the icon gives the opposite impression that they are locked out of it and cannot access it.
I have some initial thoughts on potential changes:
The unlocked lock emoji seems a natural choice, but it doesn’t look that different.
I agree with unlock-alt solid from fontawesome. It looks pretty close to the existing icons in style, so it won’t look out of place in the UI. And it’s simplicity of form means it’ll still work well at very small sizes, like in the category listings on the homepage.
I don’t think lock+plus or lock+eye really add to the meaning.
Let me know if you need help adding it to the theme @MelissaGraham.
appearing next to the names of some categories could be giving the wrong impression.
seems a natural choice, but it doesn’t look that different.
or the eye 
might work?
or 
