It’s not deleted, just blocked by 3rd party client-ids.
I had the same issues a couple of days ago. Interestingly enough, if you yoink a client-id from the browser (from the network tab), and using that client-id (which you shouldn’t, Kapp), everything works like a charm. I have no issue with removing undocumented api-s, but not providing any acceptable alternative… well that’s something else.
“Someone is playing with a big ON/OFF switch at Twitch”. Because right after my post, everything went back online. Yesterday and today the api is still blocked by 3rd parties.