The "Material Girl" is collaborating with "Juno" screenwriter Diablo Cody on the screenplay, but there have been no casting announcements.
"The truth will set us all Free!" the pop star wrote. Fellow performer Annie Lennox called her out for endorsing "dangerous quackery."
The Queen of Pop said she was ordered to pay up after comments she made at a 2012 concert in St. Petersburg, but she opted not to do so.
The singer shared the custom conical bodice Jean Paul Gaultier made for her to wear to this year's event.
The Material Girl has not been immune from eyebrow-raising statements during the COVID-19 pandemic.
"He was a wonderful, kind, gentle, wonderful actor with a great sense of humor," she said of Mark Blum.
The singer called the global pandemic a "great equalizer," while soaking in a rose petal bath.
Queen, Green Day, Avril Lavigne, BTS and other artists also are nixing upcoming dates.
The Material Girl joins a growing list of acts including BTS, Mariah Carey and Green Day who have scrapped shows because of the spreading virus.
The Queen of Pop has a deal for the Duke and Duchess of Sussex.