JSON Extracted Values Break Equality-Comparison Reflexivity (X = X is FALSE, JOIN/IN Drop Rows)

-- 1. Reflexivity broken (expected 1, actual 0)

SELECT JSON_EXTRACT('{"a":"text"}','$.a') = JSON_EXTRACT('{"a":"text"}','$.a');  -- 0

SELECT ('{"a":"text"}'->'$.a') = ('{"a":"text"}'->'$.a');                        -- 0

SELECT ('{"a":"text"}'->'$.a') <=> ('{"a":"text"}'->'$.a');                      -- 0

-- Evidence: both sides are byte-identical with identical collations

SELECT HEX('{"a":"text"}'->'$.a'), HEX(JSON_EXTRACT('{"a":"text"}','$.a'));      -- 227465787422 / 227465787422

SELECT COLLATION('{"a":"text"}'->'$.a'), COLLATION(JSON_EXTRACT('{"a":"text"}','$.a')); -- identical

-- 2. JOIN equality loses data (expected 1 row, actual 0 rows)

CREATE TABLE tj1(j JSON); CREATE TABLE tj2(j JSON);

INSERT INTO tj1 VALUES ('{"a":"text"}'); INSERT INTO tj2 VALUES ('{"a":"text"}');

SELECT COUNT(*) FROM tj1 JOIN tj2 ON tj1.j->'$.a' = tj2.j->'$.a';               -- 0

-- 3. IN subquery loses data (expected 1, actual 0)

SELECT ('{"a":"text"}'->'$.a') IN (SELECT '{"a":"text"}'->'$.a');               -- 0

-- 4. CAST variant (expected 1, actual 0)

SELECT JSON_EXTRACT('{"a":"text"}','$.a') = CAST(JSON_EXTRACT('{"a":"text"}','$.a') AS CHAR); -- 0

-- 5. Semantic asymmetry (the absurd part)

SELECT '{"a":"text"}'->'$.a' = 'text';        -- 1  (comparison with a bare string works: unquote semantics)

SELECT '{"a":"text"}'->'$.a' = '"text"';      -- 0

-- 6. Value-type matrix: only STRING triggers

SELECT '{"v":"str"}'->'$.v' = '{"v":"str"}'->'$.v' AS str_eq;   -- 0  <-- bug

SELECT '{"v":123}'->'$.v'   = '{"v":123}'->'$.v'   AS int_eq;   -- 1

SELECT '{"v":1.5}'->'$.v'   = '{"v":1.5}'->'$.v'   AS dbl_eq;   -- 1

SELECT '{"v":true}'->'$.v'  = '{"v":true}'->'$.v'  AS bool_eq;  -- 1

SELECT '{"v":null}'->'$.v'  = '{"v":null}'->'$.v'  AS jnull_eq; -- 1

SELECT '{"v":[1,2]}'->'$.v' = '{"v":[1,2]}'->'$.v' AS arr_eq;   -- 1

SELECT '{"v":{"k":1}}'->'$.v' = '{"v":{"k":1}}'->'$.v' AS obj_eq; -- 1