People get to like things. It’s ok to like whatever you like.
Even if it’s a show for little kids
Or toys. Or kids’ art supplies. Or picture books. Or YA novels.
When people like things, they’re being people who like things, not being age-inappropriate.
It’s wrong to invade spaces that are intended for young children, or to attempt to get children to accept you as a peer. That’s a boundary violation. Age matters when you’re interacting with others, and some things are genuinely wrong for adults to do.
But liking the thing is never the problem. It’s always ok to like things. Adulthood happens when you reach the age of adulthood. It is not something you have to earn by turning away from awesome things you like.