So this got lost in all the Persona 5 Royal news, but Atlus came out today to confirm that Persona 5 has sold 2.7 million copies worldwide. This comes from the Amazon JP listing for Persona 5 Royal. Last sales update had the game at 2.4 million just a few weeks back.
https://www.amazon.co.jp/dp/B07QZ1CWL6
https://www.amazon.co.jp/dp/B07QZ1CWL6