The broadcaster enters text into the “config panel” not the video or panel.
Extensions may not use keyboard input to power functionality.
I interpret this to mean keyboard shortcuts, for example like the Kappa pet, you can’t use ctrl + t or y or u to make the pet do something.
You may still be allowed to use
<input type="text" />
As there are valid reasons for this such as “hey pick your Kappa pet name”