@theguyfromthesummit cool, I did look at your screenshots for a while and managed to recreate the route in brouter, it says the ascent is 522 m and the plain ascent 452 m. So data in openstreetmap is fine. I will report it to Suunto.
Thanks to everyone reporting bugs, I know we usually forget to say it, but thanks to take time to help improve the app (and the watches).