That's strange, indeed!
My stories that have gone viral, accumulating in the thousands, are still performing well, even after the redesign rolled out.
Maybe it's because of the niche itself. Writers looking to learn more about writing on Medium is a tiny niche.
Especially compared to the stuff I mostly write about or the really popular posts on the platform.
I'd be curious if you or other writers see this on viral stories that aren't about writing.