hangar 13 explained in a note the reasons for the postponement:
"Even though we initially thought we were going out a month earlier, on August 28, finalizing everything in time for that date has become extremely complicated, due to the global Covid-19 pandemic, and the last thing we want is to compromise the quality of the experience. From the beginning this has been an exciting project for us. Many of our developers have worked on creating the original Mafia and we are all committed to fabricating an updated experience that is worthy of that timeless classic. We appreciate your patience and understanding as we make Mafia: Definitive Edition the best that our fans around the world can have. "
In the meantime, a reveal gameplay has been scheduled for July 22nd.