When you hide chat during a live broadcast, you won’t be able to see any comments, though others will continue to send and see them. All comments will be viewable in replay.
Both broadcasters and viewers can hide chat during a broadcast or replay by swiping right in iOS or swiping up in Android and tapping ‘Hide Chat.’ You can unhide chat at any time by tapping the "Chat Hidden" label in chat bar or 'Show Chat' by swiping right on iOS and up on Android. If you’re viewing from the Web, you can also enable Cinema mode by pressing 'h' to remove the display of hearts, comments, title, and app links for an unobstructed viewing experience. To get the display back, press ‘h’ again.
Related: What is limited chat?