Ask What do you do when a client wants revisions but the original brief was not clear enough to begin with?

[Edward22]

Sometimes a project starts without clear instructions, and later the client asks for many changes that were not discussed at the start. This can feel unfair because the work keeps growing without extra pay. At the same time, you want to keep the client happy. How do you handle revision requests in this kind of situation without causing conflict or working more than agreed?