PTO is accrued, is part of the compensation package, and when unused results in a check for those hours of unused PTO at the salary rate in effect when employment terminated.
The "unlimited personal time off" scam is a compensation regression from the previously standard accrued/earned PTO package.
For employees with leverage, the "unlimited time off" can turn out fine if they take advantage of it without harming their role in the company.
But, for such employees, the previous system of accrued/earned PTO is typically advantageous anyways because they will often be able to take time off or "work from home/remotely" while effectively taking time off without depleting their PTO balance, leaving it for payment when employment terminates.
In any case, for the majority of employees, "unlimited time off" is really just a loss of compensation as they don't usually have the leverage and/or diligence to take sufficient time off before termination.
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At a past startup, in an attempt to get better terms in an upcoming funding round, the executives got the brilliant idea of switching from a standard PTO policy to "unlimited". They sold it to the employees at an all-hands meeting as a compensation upgrade.
The sales and operations folks celebrated, while us engineers, who had largely taken zero vacation under continuous crunch since starting immediately asked what would happen to our respective unused PTO balances.
Their response? The unused PTO would be zeroed "now that it was unnecessary, since you could take unlimited vacation anyways."
It was a sleazy attempt to erase the unused PTO balance commitments to all employees from the books before raising the next round. At everyone's expense.
We engineers called the executives out on it, and threatened to quit immediately which would force them to cut PTO checks to all of us - and said we'd be in tomorrow to interview and renegotiate our positions if desired.
That forced them to instead freeze our unused PTO balances. We were unable to prevent them from pivoting to the "unlimited time off" plan however, everyone was effectively demoted that week. I did however receive my substantial unused PTO check when I eventually left that sinking ship.
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Hopefully that (true story) helps illustrate the difference...