Consider a larger health warning when trying to search an e2e room on web.

Anecdotally it is easy to miss the warning in the search bar when trying to search via the web client in an e2e room. So users assume that our search is simply broken.

Would it make more sense to prevent the search box appearing (with explanation) at all on clicking the search icon? Or at least have a louder warning on clicking the search icon?

A reason not to do this would be if the user wanted to search all rooms (rather than current room) so it might be worth understanding how users search today before deciding one way or the other.