Your policy is blocking ptrace from processes that don't seem like they should need ptrace (very few processes need ptrace). So why would Firefox need ptrace? Some cursory googling suggests that ptrace is used for plugins and by the crash reporter.

There are apparmor profiles for Firefox, e.g. this one: https://github.com/nibags/apparmor-profiles/blob/master/appa... Maybe you could add it to your system and see if that fixes things.