This doesn’t feel very oniony.

Yes, but they have to use a very cumbersome device that is powered by sheep and cheese to get there.

I feel it's Oniony in the fact that even children's shows creators have to speak up about how Brexit is fucking them over.

How so?

It goes to show how deeply pervasive Brexit's rotting effects have been. Were this an article about how the British have become poorer or trade restrictions are harming the economy, that would not be Oniony. But now we are talking about kids missing out on shows that help form their childhood because of Brexit.

I get that it’s bad, and this is a sign that it’s bad. But in what way does the title of the article sound like a joke, as per the the main concept of the sub?

I always thought of Onion articles as taking elements of truth and putting an absurd / satirical spin on it. I think it's pretty absurd Brexit has gotten to the point where British kids shows need to either go off the air or be made not in Britain

Nearly the opposite of the point of this sub...

Your understanding objectively wasn’t wrong, I just feel it is incomplete without the humor present in all of The Onion’s articles.