It looks like Chase has removed the main Chase Slate landing page and all Chase Slate application pages. These now all redirect to the Chase Freedom pages. It’s possible that this is due to the card being changed or website maintenance, but generally when maintenance is done it won’t redirect to a specific page and will instead redirect to the main Chase credit card page. It’s possible that Chase is temporarily pulling this card due to the COVID-19 uncertainty as Chase Slate is their sub prime card targeted towards people rebuilding or starting their credit profile and offers 0% APR no balance transfer fees.
Hat tip to @mikeoliver93