I’m in a Ducktales mood after reading the latest comic and learning that Season 2 airs in October, so, time for more headcannon: Webby doesn’t feel comfortable in closed, tight spaces. Her energetic personality makes it easy for her when she has room to move around. When she’s in a confined area, she feels uncomfortable, and is prone to panic (like she did in the Ball Pit.)
I could see it! Webby may have grown up sheltered, but she grew up in a huge mansion. She’s never had to deal with anything more cramped than those air vents she crawls in.