Things protected by an advanced trigger condition will still show up in recently used.
That is because advanced trigger conditions are evaluated after the trigger has been triggered, however before the assigned actions are executed.
So in your case F12 would only be sent when Brave Browser is active, but cmd+b will be caught in all apps.
However do you really need an advanced trigger condition?
If you want the shortcut to just be active on Brave Browser, add that browser to your list of apps in BTT and then assign the shortcut to it:
