I had agoraphobia growing up. I know exactly what it is. And I had moments of it exploring the planets. I found myself hugging to keep buildings in range and not wanting to stray out into the great wide open. For some odd reason, I got more of that in Starfield than in NMS.
I’m also still fairly early into the game, so perhaps I’ll spend more time indoors than I have so far.
EDIT, also, it kinda is the opposite of claustrophobia in some ways. There are some overlaps and nuances (both fears sometimes include fear of crowds). I had a grandparent with really bad claustrophobia who never used an elevator in her life. Ironically, we could relate on a lot. But they were still opposite issues.