How do you prevent Strava from generating the
“X uploaded their first Y in a while. Give some kudos to show your support”
Notification for all followers of user X who does an activity Y after not doing any for a while?
(as an option for X that is, not for each individual follower)
This might be worth submitting as a feature request (in the “Ideas” section where people can vote), I’d personally welcome if it was added in the privacy controls... I admit that this notification has always had strong creep vibes for me. 
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