steam reviews visibility change from public to friends only. any ideas?

half of my reviews went from public to friends only without me making this change myself. anyone have any ideas on why this would occur? i changed them back no problem, but i'm curious AF as to how this would even happen.

my only possible theory is that it's some auto-moderation thing Steam is doing in response to the user being mass reported-- i had a community ban from sept11th through the 15th, though i have no idea when the visibility change occurred so it could've been during the ban or way after. don't think it was before, i seem to remember seeing the text "31 reviews" under my name when i posted the item that ultimately got me mass-reported, so.

any ideas? google isn't coming up with anything, and while i'm not super bothered by the change itself my curiosity as to how it even happened is killing me here.