In Finnish, there's a pithy expression Siitä puhe mistä puute, which literally if somewhat awkwardly translates as "talk is about what is lacking".
For example, if you fly into a country and find the streets full of massive billboards proclaiming that the many races of the country are united behind the Glorious Leader, who is making the economy strong and ensuring everybody has enough to eat, it would be reasonable to suspect that the billboards are attempting to paper over the reality that that most people hate the Glorious Leader, there are racial tensions, the economy is terrible and there are food shortages. But the expression can also apply to much more pedestrian situations, like a couple on the verge of divorce insisting publicly that everything is just fine, or the CEO proclaiming that rumors about discontinuing a badly-selling product and laying off everybody involved are completely false and untrue, or an oil company strip-mining the Arctic buying full-page ads to tout their investments in solar power.
Is there a way to convey this in English? The lady doth protest too much comes close, but this seems more targeted at a specific individual: for example, the Glorious Leader could be accused of protesting too much if they go on CNN to repeatedly deny all claims of famine before the reporter gets around to asking about it, but this doesn't seem applicable to an entire state-run propaganda campaign.