Changing FTP changes all previous training score data
Currently, updating your FTP causes a mass change to all prior workout data, rendering all the past performance data inaccurate (the data is only as good as the FTP it is attached to).
If - 12 months ago - my FTP was 250, and today I update it to 300, all my previous workouts are "downgraded" in their relative training intensity and stress scores. Which does not reflect reality because 12 months ago, these workout felt intense and stressful for my fitness level back then.
What should happen is that when you update FTP, only workouts after the change are affected.
Strava people - this is costing you money! Athletes who are serious about their data are using competitors' products and free alternatives. I am forced to use GoldenCheeteah, if you changed this one bug I'd be a premium Strava member.