anyone know what this symbol is?

so i was riding around as usual and i always take the same route. on this specific road i usually have enough time to gather enough speed to end up going 25mph which is the max my scooter can go. when i went today, it capped at 18. when i was coming back home i noticed it kept going down until it reach 4 mph. i think this symbol might have something to do with it. at some point even though i was going full throttle it eventually stopped moving. i had to push it all the way home. please help