That is an employment negotiation, not an immigration rule. The petition fees in the USCIS fee schedule are the employer's cost as petitioner; relocation packages and any clawback are set by contract. Read what triggers repayment and whether an immigration refusal counts.
Separate the government's costs from the company's terms
The employer pays the I-129 filing fee and any additional statutory fees for L petitions, and may choose to pay for premium processing; those figures are listed in the current G-1055 and should not be recovered from the employee in a way that is inconsistent with the employer's obligations. Everything else is contractual. Hypothetical example: a Sainte-Brigitte-de-Laval operations manager is offered a relocation package with a clause requiring full repayment if she leaves the U.S.
affiliate within two years. She should ask whether the clause is triggered if the petition is refused, if the extension of a new-office case is denied, or if the company itself ends the assignment, since none of those is within her control. She should also ask how moving costs, temporary housing, tax preparation and the spouse's licensing are treated, and whether salary is paid by the U.S.
or the Canadian entity, which affects both tax and the evidence of who employs her. None of this belongs in the immigration file, but all of it should be settled before the family commits to anything irreversible.