I used to work for f2p game companies and they also used this as a standard trick. On top of suppressing negative reviews they would only ask you to rate the game immediately after something good happened in the game. You leveled up, or got a good prize, or whatever. They would craft these entire on-rails onboarding experiences where you seem to win a jackpot early on, then ask you for a review. They'd build out these flows and user test them and iterate until it psychologically produced the intended ratings