This is already possible with tiny or invisible text, I don't think browsers are...

		remram on May 12, 2021 \| parent \| context \| favorite \| on: Google Docs will now use canvas based rendering This is already possible with tiny or invisible text, I don't think browsers are trying to protect from that. The protections that exist are to prevent sites from reading your clipboard or replacing it without you clicking on anything, other than that the site already has control over what goes in it.