Hey @RinIoM, 
Hello and thanks for your post. Strava is a community-moderated network and we rely on our community of athletes to monitor the integrity of our leaderboards. There is a way for you to address bad data but you need to log into your account via the website to do so. You can find more info here.

We're sorry for the trouble and this will also be shares with our challenges team so they are aware of this. 

I found the same issue with the May 2025 400 Minute Challenge, where the top 50 had recorded more hours activity than there were hours in the month.

After some digging through their activities, it appears that going swimming with a Suunto watch (Suunto Race and Suunto Vertical were the devices consistently listed) causes the occasional erroneous lap time of between 590 and 600 hours. Go for a couple of swims, or a long enough swim to trigger the issue more than once, and you can easily rack up over 1000 hours.