It’s similar to what FH5 has, there’s some impact on the handling and attitude of the car when traveling over puddles. The effects also come through the controller/wheels.
Some parts of certain tracks can puddle in real life, and we know race cars will actively avoid those areas when racing in wet weather. This can create more race challenges, requiring players to be more skilled and aware of track evolution.
The area where puddles occur need not be 100% like real life but there is some resemblance.