https://communityhub.strava.com/insider-journal-9/an-update-to-our-developer-program-13428
The gist of it is that Strava just killed its free API, and will now require developers to have a subscription.
At Strava, we care deeply about developers, and the health of the developer ecosystem. There are now 241,000 Strava API developers, up from 185,000 last year. Starting today, all current and future applications will automatically receive access to the Standard developer tier. This allows you to serve up to 10 athletes and start building immediately, completely eliminating the previous queue.
This essentially kills thousands of tools people build using the free API.
If you’re looking to move away from Strava, so far I’ve found two open source alternatives:



Sorry to say that most sport devices are not supported by gadget bridge
Its FOSS. Be the change you want to see in the world.
Well, due to hardware encryption keys and such, it’s not that easy… Also many devices supported only works after sniffing the keys from the official apps. Which is not a viable approach in my opinion…
Unfortunately, it’s not that easy. Garmin is still one of the most open brands, you can always copy activities from USB cable if you don’t want to use the proprietary Garmin app.