Johnson, 26, was the Suns' first-round pick in the 2019 NBA Draft, and after being used primarily off the bench in his first three seasons, the three-point specialist broke into the starting lineup full-time this season.
He took Jae Crowder's starting role in doing so, leading to a relatively messy break-up between Crowder and the Suns, as he is now away from the team awaiting a trade and according to ESPN's Brian Windhorst, Johnson's injury situation is not impacting that decision.
Johnson started the season averaging a career-high 13 points per game, and he leads the Suns in three-point makes per game (2.8) while shooting a career-high 43.1 per cent from long range.
In the game before he suffered his injury, Johnson led the Suns with 29 points on 10-of-17 shooting in a 116-107 win against the Minnesota Timberwolves.
After not coming to an agreement for a contract extension in the offseason, Johnson will be an unrestricted free agent at the end of the season, meaning the Suns will have the option to match any offer he receives from other interested teams.