【Ethereum】送信者が特定の条件の元、ethを送金

sendではなく、recipient.callで送信してますね。

pragma solidity ^0.8.0;

constract ConditionTransfer {
    address public owner;
    address payable public recipient;
    uint256 public unlockTime;

    constructor(address payable _recipient, uint256 _unlockTime) {
        owner = msg.sender;
        recipient = _recipient;
        unlockTime = _unlockTime;
    }

    receive() external payable {}

    function release() external {
        require(msg.sender == owner, "Only owner can release funds");
        require(block.timestamp >= unlockTime, "Funds are locked");

        uint256 amount = address(this).balance;
        require(amount > 0, "No funds to send");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Transfer failed");
    }
}