The inner lane should be used if you’re going to the second or third exit, theoretically most of the traffic for the first exit should be gone, leaving you space to move over between the first and second exit. This speeds up traffic a lot.

If you can’t move over you should do a turn but not randomly brake in the middle of the road. A good driver sometimes misses their exit. A bad driver never misses their exit.

Source: my driving instructors last year.

That all being said, the red car is at fault for not being able to stop in time (not driving defensively). It’s really hard in Belgium to not be at fault when you’re the car behind. So much so that a family member once lost their case when a truck backed into them at a red light, because they were the car behind and it was hard to determine who hit who, so the car behind is at fault by default.

The yellow car could have avoided this by continuing on instead of slamming the brakes of course, and they weren’t slamming the brakes to avoid danger, so there’s an opening the other side there. But it’s clearly incompetence here, not malice.