Uncategorized/<Welcome to Discourse> on iPhone

On my iPhone (Safari, running iOS 13.5) there is an „Uncategorized“ entry with one topic „Welcome to Discourse“ on top of all other categories. This does not appear on my iPad or my laptop, does anybody know what’s up with that and how to get rid of it?

To clarify, this „Uncategorized“ category appears on the Categories view of the Main page.

I see it too on my Android phone. The “Welcome to Discourse” message is apparently supposed to be customized for this particular message board, but it hasn’t been.