Every pope since Fatima expressed belief in it
What exactly did they express believe in? Did they express believe in all the heavenly revealed messages as handed down by all the literature and trad.inc and fatima.org and fatima.pt? Could you, forlorn, please be so kind to specify what exactly you mean to say, and then post some source to backup your claims?
There is no doubt that a Sanctuary was build in Fátima, and that veneration was allowed. But I ask you: if there was a Pope who expressed belief in the messages of Fátima, as understood by Ascetik, obviously by you, and by others here on CI, that Russia has to be and wasn't yet consecrated in a way to please Our Lady, then why didn't they do it? How does the fact that they didn't, not indicate that they don't care about all the apocryphal messages, published by irrelevant sources?
and the local bishop declared the apparition worthy of belief(the same way it works for every apparition - no apparition has ever been approved directly by the pope).
Declaring "the apparition worthy of belief" doesn't mean that the local bishop declared all the many apocryphal messages found on the fatima.inc sites, allegedly having been revealed by Our Lady and/or Our Lord at various points in time, to be credible. Still you seem to suggest, that he did, but you don't provide any sources.
Why the pope never performed the consecration in unison with all the bishops I don't know, but to call an approved apparition apocryphal is just ridiculous. I understand that just because an apparition is approved as worthy of belief doesn't mean it's true or has to be believed, but it's disrespectful to call something the Church approved apocryphal.
You say: "Why the pope never performed the consecration in unison with all the bishops I don't know". Well, the obvious idea is: they don't listen to what is published by unauthorized sources!
You say: "to call an approved apparition apocryphal". I don't call the apparitions apocryphal, rather I call the messages apocryphal. And that's what they are. No apostolically authorized shepherd has proposed these messages as relevant to Catholics. If you complain, please quote the Magisterium of the Church, proposing the content of the messages to be revelation. If that's to much asked, quote a single bishop, presenting the text of some or of all the messages and declaring that Catholics should take a look at them, and consider them to be possibly true, or maybe consider them to be absolutely true.
But what am I asking? forlorn, you do well know, that such hasn't happened and such is not the case.