Okay, I don't know if the site is rigged or not.
But from a statistical point of view, it is not really that impossible to see 21 reds and 9 greens in 30 bets with p=49.5%.

Probability to win = 49.5%
Probability to lose = 50.5%

Probability to get 21 reds and 9 greens in 30 bets = 30! / 9! / 21! * (49.5%)^21 * (50.5%)^9 = 1.18%.

The chance is small, but it is not that rare IMO.