Incorrect KMs recorded on Health App

Hi I recently upgraded to an IPhone 13 ProMax and needed to resync my apple watch to my new phone. Now when out hiking I get extra kms added to my distance walked. I know this because a.) I know the distance covered for some walks and b.) when walking with my husband he records less km for the same distance. It doesnt double the kms so its not adding the two together, but it is significantly out. How can I fix this ?