Is it possible to stop the chat from popping up when making a livestream fullscreen?

Only seen this start happening today but when I'm watching a live stream and I put it in fullscreen the chat pops up and takes up half the screen. It's annoying but you can just hit the X and close it so it's not big deal but I've just gone onto a stream with the chat disabled and when you fullscreen the box still pops up but there's no button to close it. Anybody know a way to resolve this or even better to get it to just stop popping up at all when I go to fullscreen?

You can see what I mean here:

https://imgur.com/FUK690f