Hello,
Thanks to everyone who has commented and provided feedback. The testing phase is completed and these notifications are now in production.
While this cannot be completely disabled, you do have the ability to disable the push notification. Push notifications are "pushed" to your mobile device when the Strava app is either closed or running in the background.
This can be turned off by going to:
You Tab
Settings (top right)
Push Notifications
Un-toggling Device Activity Synced
The push notification settings do not affect the in-app notifications you receive in the mobile app or on the Strava website.
Again, we appreciate the feedback and it has been passed along to the Team.