"conducting its second round of layoffs in 2024, reducing its workforce by another 5%"
doesn't sound consistent with
"They still have 5500 employees, and are working like hell to keep them."
JPL is the victim of Congressional budgeting of NASA. Maybe JPL is trying to keep its staff together, but if the customer(s) don't have the cash to buy its products, then they can't make the products, can't get the income, and can't pay their staff that makes those products.
NASA has to play the game in both directions. These projects take long time periods - far longer than annual budget cycles or even administrations with their changing priorities. And the rate of progress is often limited by budget. So, NASA needs to constantly decide if it needs to cancel projects or try to keep them going "on the back burner" until Congress decides to change its priorities and/or budget to support them again. Plus, sometimes Congress explicitly directs NASA to prioritize some project or stop some project.
It is not feasible to start-stop- restart projects that require specialized knowledge and skills. The necessary people leave and are not necessarily going to come back to a company that laid them off. Restarting a "killed" project is not much different from starting a new project with new staff. Unless the contractor can find some way to keep the suddenly unemployed staff on-payroll by assigning them new tasks.