Leasing cars, the downsides?

Moin, Firstly, I come from a place where dealing with loans and interests is forbidden... so a lot of trading concepts are new to me and I can only be skeptical if they sound too good.

I've been looking into leasing a car, so far, everything sounds positive: - you pay less - you don't have to worry about selling the car later - the dealer might enforce you to only use original and authorized parts (sounds good to me?)

But still, why isn't everyone on a new leased car in Germany? Where is the catch?

Thanks :)