In this article, Bloomberg claims that undisclosed manufacturing changes at one of the largest producers of anti-malaria bednets have led to distribution of hundreds of millions of ineffective (or less-effective) bednets, and that this problem is linked to an increase in malaria incidence in the places where these nets were distributed.
The manufacturer is Vestergaard and the Against Malaria Foundation is among their clients.
Bloomberg has a steep paywall but the link here gives free access until March 2.
According to the article, there are high-performing PFAS alternatives, but they are more expensive. So instead Verstergaard allegedly went with the cheaper, lower-performing option.