Financial fair play is not league restricted, all clubs in Europe are regulated, Of course there a some loopholes in the rules and that's why PSG were able to sanction deals for both Mbappe and Neymar in the same season.
As long as you are selling and buying at the same time you are still within the FFF rules and that's what PSG does, they release players or make sales every season to stay within the limit, there are so many players leaving this season because of the incoming ones.
Man City are even in a better situation compared to PSG, because playing in(winning) the premier league definitely generates more revenue than in the french league.
Is not about the income generated from trophies it's the income generated from players sales that's what the rules is all about, we both know that PSG has more player sales than Man city almost all the players who left City left on a free transfer.