On the web browser you can clear notifications at the top of the chat (such as a hype train) by clicking the 3 buttons. On mobile, there is no option to clear notifications. And it is a huge pain because when a notification such as a hype train shows up in the chat, it makes the chat bigger (half the screen) for the entire duration. So every time a hype train starts (which happens a lot in bigger channels), chat takes up half the screen and you are forced to watch without chat if you want to be able to actually see what’s going on in the stream video.