Has YouTube suddenly gone behind an app?

I don’t even know if I’m asking this right. Luckily I know that some jellies are way ahead of me on the technology and can figure out what I’m trying to ask.

Until recently, I’ve taken for granted how easily I could play YouTube videos on my Kindle Fire. Now all of a sudden, the whirly thing just keeps spinning as if downloading, and they don’t start.

There’s a button that says Subscribe. Do I have to subscribe to something now in order to see YouTube on my tablet? I don’t see any explanation for this or a link for more information and have failed to find any via Google.