Is this the contract Ragnow was playing under when he first announced his retirement or is it a "new contract"when he decided he was coming back? If it's the latter and he did not pass the physical or whatever then I think the Lions are right for seeking a portion of what he received from the team.
Trusting A-I on this, he received a $6 million signing bonus in 2021 (his last contract) also a $18 million option bonus in 2022. (That looks like part of his extension) The contract runs out at the end of 2026.
You could argue that he did not fulfill the terms of his contract, especially when he retired in late Spring 2025.
From Overthecap.com
https://overthecap.com/lions-force-c-frank-ragnow-to-repay-portion-of-bonus-money#google_vignette