The recipients are the borrowers. An owner of the collateralized debt tokens can burn them to withdraw the proportional collateral locked when the underlying proportional debt is paid before the maturity date
For example, there is a user who owns a Collateralized Debt token of a pool expiring on 12-30-2021 with 2 WETH locked as collateral against a debt of 300 DAI. If the user repays 300 DAI debt before 12-30-2021, the user can burn his/her collateralized debt tokens to withdraw the 2 WETH locked as collateral. If the user did not pay the 300 DAI debt, the collateralized debt tokens will lose the repay debt functionality, thus, the user will never be able to withdraw the staked collateral.