If you have participate Polkadot council election, you will find there are still some DOT locked in the block explorer even after your unbonding.
So you need to do the unvote process to get your DOT fully unlocked, the steps are:
Open PolkadotJS Dapp
The the menu click ‘Governance’-‘Council’, and then click “Vote”
Click “Unvote all” and sign the transaction
Based on the voting weight you select when election, there will be different unlock period. By default, the unlock period is 0 days, and you will get your DOT fully unlocked when the transaction has confirmed.