Subquery gives wrong results: using JSON_TABLE in SELECT part

MariaDB [(none)]> select version();

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

| version()              |

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

| 11.4.2-MariaDB-ubu2404 |

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

1 row in set (0.001 sec)

MariaDB [(none)]> select d.id,d.doc

    -> ,(select a from json_table(d.doc,'$[*]' columns(a int path '$.a',b int path '$.b')) t where t.b=2 limit 1) found_a

    -> from (

    -> (select 1 id,'[{"a":3,"b":1},{"a":2,"b":2}]' doc)

    -> union all (select 2,'[{"a":6,"b":1},{"a":4,"b":2}]')

    -> ) d

    -> ;

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

| id | doc                           | found_a |

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

|  1 | [{"a":3,"b":1},{"a":2,"b":2}] |       2 |

|  2 | [{"a":6,"b":1},{"a":4,"b":2}] |       2 |

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

2 rows in set (0.000 sec)

MariaDB [(none)]> select d.id,d.doc

    -> ,t.a found_a

    -> from (

    -> (select 1 id,'[{"a":3,"b":1},{"a":2,"b":2}]' doc)

    -> union all (select 2,'[{"a":6,"b":1},{"a":4,"b":2}]')

    -> ) d

    -> join json_table(d.doc,'$[*]' columns(a int path '$.a',b int path '$.b')) t on t.b=2

    -> group by d.id

    -> ;

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

| id | doc                           | found_a |

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

|  1 | [{"a":3,"b":1},{"a":2,"b":2}] |       2 |

|  2 | [{"a":6,"b":1},{"a":4,"b":2}] |       4 |

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

2 rows in set (0.000 sec)