"Slavery is any system in which principles of property law are applied to people, allowing individuals to own, buy and sell other individuals, as a de jure form of property."
https://en.wikipedia.org/wiki/Slavery
Living paycheck-to-paycheck or hand-to-mouth like most humans lived for most of human history does not make one a slave. To state otherwise is to compare mere existence to slavery.
Unless someone is an actual slave under bondage or with threat of coercion from another person, they are always in a position to leave a job. Doesn't mean they are free of consequences, like no longer getting money because they are no longer willfully trading their labor for compensation, the same way that someone farming the land will stop reaping the benefits of their labor once they stop engaging in farming behavior or if someone living as a hunter/gatherer will stop collecting sustenance when they stop hunting and gathering. At no point are any of those people slaves because no coercion is involved.