I never set the post for no-index.
My post was silently deindexed after I change it.
I know by using site:domain search in Google.
I have switched some of my posts.
They all got the same deindexed.
The ones I didn't touch stays in the index.
Google search console never inform anything odd as well.
Thanks Fleeky, I do see often that people used a post for the PP, that looks bad on the blogroll, I will share your training with them when I see this again:) nice artistic arrows used:)