I got an email alert from Strava stating that they’re making some changes to their login flow on Oct 15th. In that email, they say:
Look out for another email with comprehensive details about refresh tokens and the migration period on October 15, 2018.
But that’s too late - I may not be able to update my code between the time that their explanation email comes and the time that they switch over the authentication flow, assuming they send the email before they make the change.
I’ve emailed their development team to try & get further details, but there’s a chance that logins will stop working tomorrow and won’t work again until I get details from them and release code to sort things out.