Why don't mathematicians believe OpenAI solved Millennium Prize problem?

OpenAI has claimed its model solved the 9-year-old Navier-Stokes problem, one of the seven Millennium Prize problems, in 88 hours. Mathematicians, however, remain sceptical as the 100-page proof has not been made public or independently verified. OpenAI's model is also suspected of allegedly scooping unpublished mathematical drafts developed using AI by mathematician Tristan Buckmaster.