tirer les marrons du feu

to do the risky work while someone else gets the reward

The one who suffers isn't the one who gains. Describes doing the dangerous, thankless bit while somebody else pockets the benefit.

Les stagiaires tirent les marrons du feu pendant que les cadres récoltent les primes.

The interns do the hard, risky work while the managers collect the bonuses.

Comes from La Fontaine's fable Le Singe et le Chat (The Monkey and the Cat), where a monkey talks a cat into fishing chestnuts out of a fire, then eats them all while the cat is left with burnt paws.