Ross posted five receptions for 142 yards and two touchdowns, including a 77-yard punt return touchdown, against Iowa last season.
Mupoyi hits the portal with three years of eligibility remaining.
Rust became the sixth former Lady Lion to find a new home this spring.
Penn State fell in overtime despite holding a three-goal lead in the fourth quarter.
Dee looks to find a new home after one season in Happy Valley.
Mitchell became the third Nittany Lion to hit the portal this spring.