Yes the new mirror link (.kim) is official link from Stake, it was given in the telegram channel few days ago. I believe it was at the time when many links seems to be inaccessible. Some links were not working few days ago, that's why Stake gave a new mirror link but it is not added in the mirror link list at playstake.io In the last few days there were many complaints from players because of access difficulties but I think it is all fixed already. Even though the information under playstake.io that all links are offline, in fact they are all working. Perhaps needs an update for the playstake.io site.
I think Playstake says they are offline because when it tries to connect them to test if they are working or not, it must be rejected by the Cloudfare security LOL. They should whitelist it or find another way to display the mirror sites status because currently it's misleading for users looking for a mirror.
Besides that access difficulties don't seem to be fixed yet either, because many people are complaining here and on social medias about those issues.