It sometimes happens that breeders have to part with their cats for various reasons (misunderstanding, end of career, deserved retirement).
They are generally adult cats, often "retired", for whom the breeder thinks they deserve a peaceful life, in a home that will welcome them until the end of their days.
These cats have the advantage of being already adults and the breeder will be able to tell you what are his habits and what is the character of the cat unlike a kitten where everything is still to be discovered!