JSON_QUOTE emits utf8mb4, JSON_CONTAINS compares raw bytes

CREATE TABLE tl (a VARCHAR(10) CHARACTER SET latin1);

INSERT INTO tl VALUES ('é');

SELECT (CONCAT('["',a,'"]')), a MEMBER OF (CONCAT('["',a,'"]')) FROM tl;

SELECT (CONCAT('["',a,'"]')), a MEMBER OF (CONCAT('["',a,'"]')) FROM tl;

(CONCAT('["',a,'"]'))	a MEMBER OF (CONCAT('["',a,'"]'))

["é"]	0