Ask Why do some clients hold back final payment until the freelancer agrees to extra work never discussed before?

[Edward22]

This is one of the more frustrating situations a freelancer can find themselves in. The project is finished, everything was delivered as agreed, and then the client suddenly brings up additional work as a condition for releasing the final payment. It feels like a bait and switch, and it puts the freelancer in a difficult position because the money is already owed. A contract should protect against this, but not every situation is that clean. Has this ever happened to you, and how did you handle it without losing the payment you had already earned?