JSON_ARRAY_INTERSECT returns an incorrect result

CREATE TABLE t_arr (

  id INT PRIMARY KEY,

  a LONGTEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_bin CHECK (JSON_VALID(a)),

  b LONGTEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_bin CHECK (JSON_VALID(b))

);

INSERT INTO t_arr VALUES

  (1, '[1,2]', '[9]'),

  (2, '[1,2]', '[2]');

SELECT id, JSON_ARRAY_INTERSECT(a, b) AS actual FROM t_arr ORDER BY id;

-- 1	NULL

-- 2	NULL

SELECT JSON_ARRAY_INTERSECT('[1,2]', '[9]') AS expected_row1; -- NULL

SELECT JSON_ARRAY_INTERSECT('[1,2]', '[2]') AS expected_row2; -- [2]