Steps to reproduce:
Open any website, for example http://crpgaddict.blogspot.com/, and press "Pg Up". The browser window scrolls down to show the end of the content, as if you had pressed the "Home" button.
The same happens on that website when you press "Up" or "Home", though some websites only have this behaviour when you press "Pg Up"
Safari does not behave this way.
Expected behavior:
Pressing Home or Pg Up should do nothing when you're at the top of a web page (at least, Safari and Chrome behave that way)
Orion, OS version; hardware type:
Version 0.99.110-beta (WebKit 613.1.12)
MacBook Pro (Retina, 13-inch, Early 2015)
MacOS Monterey