Problems with a stored function EMPTY() on upgrade to 10.6

CREATE OR REPLACE FUNCTION empty(a VARCHAR(128)) RETURNS int RETURN LENGTH(a)=0;

SELECT empty('1');

MariaDB [test]> CREATE OR REPLACE FUNCTION empty(a VARCHAR(128)) RETURNS int RETURN LENGTH(a)=0;

Query OK, 0 rows affected (0.007 sec)

MariaDB [test]> SELECT empty('1');

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

| empty('1') |

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

|          0 |

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

1 row in set (0.002 sec)

CREATE OR REPLACE FUNCTION empty(a VARCHAR(128)) RETURNS int RETURN LENGTH(a)=0;

SHOW WARNINGS;

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

| Level | Code | Message                                                      |

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

| Note  | 1585 | This function 'empty' has the same name as a native function |

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

SELECT empty('1');

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '('1')' at line 1

+%token  <kwd> EMPTY_SYM                     /* SQL-2016-R */

+%token  <rwd> JSON_TABLE_SYM

+%token  <kwd> NESTED_SYM                    /* SQL-2003-N */

+%token  <kwd> ORDINALITY_SYM                /* SQL-2003-N */

+%token  <kwd> PATH_SYM                      /* SQL-2003-N */