Platinum Rank decays, Despite Riot saying it does not decay

According to Riot's official support site : https://support.riotgames.com/hc/en-us/articles/204010760-Ranked-Play-FAQ#h3q1 And a tweet from a rioter https://twitter.com/RiotSapMagic/status/1062439601854267392 Platinum rank will not decay in season 9

Imagine my surprise when I get greeted with this notification https://i.imgur.com/FDRHcLL.png Despite my rank being plat 1 https://i.imgur.com/NBjWd1q.png

While this might not be a big deal for everyone, it is for me as I dont want to play 1 game every month to keep my ranked progress, and if I knew riot lied and platinum does decay i would have never played my provisionals so early in the season

so what exactly is happening, did riot just not bother implementing it, did they back down despide updating their support site when the season start, is this notification false.

Do I have to play a ranked game to not decay, cause I really dont want to if I dont have to