I have noticed in the iOS app a very weird bug which I've managed to reproduce consistently. The bug causes a Twitch stream to still play on background even after changing it or closing the stream.

These are the steps to reproduce the bug:
1. Open any stream where you can subscribe to them (affiliates+)
2. Click the blue "Subscribe" button and click "Subcribe".
3. Select two months, then one month again, then click "Buy Subcription Token".
4. Then iOS asks you to pay, press cancel.
5. Do this again as you try to gift five subs. Do it, then cancel it.
6. After all of this, change stream.

The previous stream which you tried to subscribe to will not be interrupted, and even if you re-open the same stream, you will hear duplicated audio.