TO_DATE: TO_CHAR with new ISO 8601 year format elements sometimes returns NULL without warnings

MariaDB [test]> select to_char(now(), 'IYYYYYYY');

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

| to_char(now(), 'IYYYYYYY') |

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

| NULL                       |

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

1 row in set (0.001 sec)

select to_char(to_date('2026','YYYY'), 'IYYYYYYY') as x from dual;

X

20262026

MariaDB [test]> select to_char(now(), 'SYYYYYYYY') as x from dual;

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

| x        |

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

| 20262026 |

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

1 row in set (0.001 sec)