Unless G2 decided to go back to "the old way" of doing things, I doubt if there's any flasher. Nor would there be a brake switch. It's a position sensor. The BCM takes that input and does the brake switch function. (As well as acting as the flasher).Do the hazards still work in the rear? I would want to rule out bad bulbs. Esp since they are separate bulbs for each. You could be looking a faulty brake light switch and or turn signal flasher. if it is not the bulbs.
Agreed I really don't know how the lights are set up but unless it is some came unplugged IDK how the wiring is done. I am still thinking old brake set ups. So probably a dealer issue.Bottom line, short of a the BCM or a connector, I'm not seeing a single point of failure that would take out so many things. (I'm assuming the turn signal bulb is separate from the brake light. I do know the G2 did away with the amber turn signal in the rear, so it might not be separate.) This is why I'm questioning a connector coming a part. The alternative is the BCM itself. Expensive and requires reprogramming. I'd imagine your car is still in B2B warranty, so if it's not simple and cheap, it's best to make it a dealer problem.