At one point I had a user script that prevented certain key combinations from being intercepted. Worse than discourse is a hosting platform I was encountering frequently for a while, where pressing esc to stop the page from loading instead caused the website to switch pages to a login prompt for the site owner. Other offenders that annoy me include intercepting alt+d (focus address bar), Ctrl+n (new window, outlook captures this), Ctrl+t (new tab), Ctrl+a (select all), and other common keyboard functions.

Fix: Just add a dummy onkeyup function to the document root and body elements, and set @match rules for whatever sites annoy you. Occasionally you'll also need the more generic event handler function as well.