Gamemaster screens aren’t there to prevent #TTRPG players from peeking and cheating. They prevent spoilers (such as when you have a Bestiary book open with a big-ass monster illustration on the page), and add vertical real estate for extra information that would otherwise not fit on the table.
Ah, finally, it is that time of the year during which walking outside my house without paying attention gets me a face full of spider webs, possibly with the spider