JSON_DEPTH returns wrong results

MariaDB [test]> SELECT JSON_DEPTH('[10, {"a": 20}]');

+-------------------------------+

| JSON_DEPTH('[10, {"a": 20}]') |

+-------------------------------+

|                             2 |

+-------------------------------+

1 row in set (0.01 sec)

MySQL [test]> SELECT JSON_DEPTH('[10, {"a": 20}]');

+-------------------------------+

| JSON_DEPTH('[10, {"a": 20}]') |

+-------------------------------+

|                             3 |

+-------------------------------+

1 row in set (0.00 sec)