I have a Honda Jazz Hybrid 2021, since the cold weather its -5C when I brake the warning comes up "Object Approaching", there is nothing in front of me, & yes I can cancel  the warning, but still left with the bleeping for 30 seconds.

Sometimes it can be a build up of dirt on the sensor(s) but judging by the cold weather we are currently experiencing I would say it may be a frost build up over the sensor.

Try cleaning it before setting off next time and see if that makes a difference

Yes I was driving a friend's car the other day and the back sensors were beeping even though nothing was there, it was cause of ice or frost build up on it. Once it had melted the noise stopped. All good 👍