Will the third party be jointly and severally liable for unpaid wages when the property is outsourced and cleaned?

Not responsible. If the property outsourcing cleaning to a third-party company, the unpaid wages of the third-party company should usually be borne by the company, not the property company, and will not be jointly and severally liable. Property companies have the responsibility to choose legal and reputable third-party service providers and sign contracts with them to stipulate the rights, obligations and service standards of both parties.