TRUNCATE forces decimal format for string arguments (internally inconsistent)

SELECT TRUNCATE('0x10', 1), TRUNCATE('abc', 1), TRUNCATE(0, 1);
– MariaDB: '0.0' '0.0' 0 <-- string inputs yield '0.0', numeric input yields 0 — self-inconsistent
– MySQL: 0 0 0
SELECT CONCAT('X', TRUNCATE('0x10', 1));
– MariaDB: 'X0.0' MySQL: 'X0'