At SummerSlam, Roman Reigns returned after five months away with more of an edge to his character. The Big Dog then firmly established himself as a heel on SmackDown and at Payback as he aligned himself with Paul Heyman and used underhanded tactics to win the Universal Championship.
Fans have been crying out for WWE to turn Reigns heel for years and Vince McMahon seemingly finally listened to the audience. Paul Davis at WrestlingNews.co reported the boss realised the company couldn't just keep doing "the same thing" and expect Roman to finally become a top tier star on the level of John Cena.
Therefore, WWE decided to turn him heel as they believe fans will likely cheer a more edgy version of Reigns once they can attend shows again. The Universal Champion will then revert to being a babyface, but retain his new heel persona.
Davis also noted WWE originally planned to do the heel turn after WrestleMania 36 whereby Reigns would have had a chip on his shoulder after defeating Goldberg. The plans were scrapped, however, after Roman went on hiatus because of the COVID-19 pandemic.