From the Mystics website:
Washington Mystics Head Coach Mike Thibault announced that forward Aerial Powers suffered a left gluteal injury in the team’s recent preseason game against the Minnesota Lynx. Powers is expected to be out for approximately two to four weeks.
Washington acquired Powers in a mid-season trade with the Dallas Wings in 2018. A 6’0 forward, Powers was selected in the first round (fifth overall) by the Wings. She averaged 5.1 points per game and 2.3 rebounds per game during the Mystics 2018 playoff run.