Any vibration felt while braking that is actually caused by the brakes would stop once the bike stopped rolling. So you either don't have a braking issue or have two separate issues.
Is it perhaps a pulsing rather than a vibration while braking? That would be more common. If so consider warped rotors.
If there's a vibration at idle with the bike not moving a motor mount is a potential problem. So is the exhaust or other engine mounted part contacting the brake pedal or something else it shouldn't be. Compensator and other engine issues can give the impression you describe also. Some of these could present while moving and while sitting still. Warped rotors would only be felt while braking.
Unfortunately many possibilites for a vibration. Work and check methodically. Front to back, top to bottom or whatever other system works for you. Just have to be sure you don't skip anything.