Issue with outside temperature sensor…dashboard temperature display continiously increases during drive.

I posted here a few days ago about the outside temperature indicator in my dashboard being wrong (it was 4 degrees Celsius outside but showed 30 degrees to begin with and increased to 45 degrees during a 50 mins drive at the speed of roughly 90km). The consensus seemed to be that the ambient sensor may have malfunctioned.

That incident appears to be a one off (the car was super dirty and has now been washed) and now it seems to start with the right temperature but it increases during the drive. For example this morning, the outside temperature is 8 degrees. When I started the car it showed exactly 8 degrees. But it increased about 7 degrees to 15 degrees during about a 35 minutes drive at the speed of roughly 60km.

Could it be that the ambient sensor is not malfunctioned but simply became loose and it is sensing something else that’s hot during the drive? Any way to check this without removing the front bumper? Or could it be another issue altogether?

Would it be better to just take it to the dealership? I drive a mazda 3 GT sport 2018.