I'd prefer there be no default list.
I've used Brave, LibreWolf, and a half dozen other browsers whose built-in protections sometimes cause sites to break for weird reasons; it's very common. It might discourage people coming from vanilla Chrome/Firefox/Edge/Safari installs where there are almost no default protections, but that's one of the many reasons I like Orion.
Toggling compatibility mode is already pretty easy IMO as its only two clicks.
I went one step further and added a programmable button to do this in a single click; you could go even further and actually set up a keyboard shortcut for it but I'm lazy.