This claim is false, and the original tweet is spreading false news that the Chiefs' victory is 'on hold'. The tweet came from a satirical "sports journalist" who is notorious for posting outlandish states regarding sports.
According to AP news, an NFL spokesperson said this claim is "absolutely false", and that Mahomes was not among the ones selected for performance-enhancing substances after the Super Bowl. Though Mahomes did suffer through an ankle injury in the second quarter of the Super Bowl, he fought his way through redemption and led his team to a victory over the Philadelphia Eagles.
https://apnews.com/article/fact-check-mahomes-chiefs-super-bowl-drugs-800317036111