My grey import Honda Bros has that feature on the front indicators. It’s fitted with twin filament (5/21W) bulbs. The 5W bulbs come on as the sidelights (& hence also with the main lights), but they go out when the indicators are used, so you get a “proper” on/off flash when indicating. I’ve had the bike for 23 years, and occasionally an MOT tester has tried to fail it because of this feature, not that they can identify a specific aspect that it fails on though - they just don’t like it. Always a pita when that happens as they don’t like to be argued with! Never had any problems with the police though.