`executeTxn` may fail

[JuanXavier]

You're passing the value in the call taken from the input parameter, as a uint256 instead of the msg.value and making the function payable.

This will revert if you pass a parameter greater than zero, as the transaction itself will have a msg.value of 0.

  function executeTxn(
    uint256[2] memory a,
    uint256[2][2] memory b,
    uint256[2] memory c,
    uint256[2] memory input,
    address callee,
    uint256 value
  ) external isOwner returns (bytes memory result) {
    require(verifyOTP(a, b, c, input), "Proof failed");
    (bool success, bytes memory result) = callee.call{value: value}("");
    require(success, "external call reverted");
    // emit TransactionExecuted(callee, value, data);
    return result;
  }

You could delete the value input, make the function payable and change

(bool success, bytes memory result) = callee.call{value: value}("");

to

(bool success, bytes memory result) = callee.call{value: msg.value}("");