Failure of one of the circuits of the braking system
If the brake fluid level has dropped below normal and the free play of the brake pedal has increased, then this indicates a failure of one of the two brake circuits.
The remaining active circuit allows you to stop the car, but more effort is needed when you press the pedal, the braking distance will increase.
For your safety, if there is a problem with the brake system, contact a BMW workshop as soon as possible.
If the display lights up "Bremsbelflge" ("brake pads"), this means that the brake pads are worn out and should be replaced as soon as possible.
Caution: Have the replacement done at a BMW workshop and use only brake pads approved by BMW. Otherwise, traffic safety cannot be ensured and, in addition, you will lose the right to warranty service.