My daughter (Employed in the US) is being forced to give a four week notice to quit her job in order to get a 100% payout of accrued PTO

My daughter found a really nice new job she’s looking forward to starting. When she gave her two week notice, she was informed that she’s only eligible for a 50% payout of her accrued PTO. If she stays four weeks, she’d be eligible for a 100% payout. She’d also have to train her replacement during this period. This doesn’t seem legal but there seems to be no laws preventing it. Just seems wrong but nothing surprises me anymore.