This article (Fortune Magazine) says that it is the data from the MyFitnesspal data breach of last year. Not a new one, that has just appeared on the Dark web. So if you changed your details a year ago, that suggests the data being sold will be out of date. Stolen Data From MyFitnessPalApp Hits the Dark Web | Fortune
“The MyFitnessPal app disclosed a data breach last year affecting as many as 150 million users. Now, some of those stolen credentials are popping up for sale on the dark web.”