Afraid Mojave is showing its age (sad).
On this site in particular, first page of Repair Guides appears as usual, but clicking any category produces a text list of subcategories. Searching a device, for example, "MacBook Pro i7," shows three laptops but selecting one again results in a text list of subcategories sans repair guide. Same results using Firefox.
It's Catalina or later from now on, huh. Please tell me I'm wrong ;-)