apple watch in motorcycle adds minutes of exercise

when i wear apple watch 4 while i'm on a motorcycle or scooter, activity signals me most of the journey as physical exercise.

i also have apple watch replacement but the problem remains.

i tried to keep apple watch in my pocket but measure exercise anyway.

also in airplane mode, measure exercise.

the only method found is to turn off apple watch, but it is annoying by going to and from work on a motorcycle every day.