SHOW CREATE TABLE reports a column as json and drops its CHECK (JSON_VALID(expr)) when expr is not the column itself: backups fail to restore or restore with a weaker constraint

CREATE TABLE t (c LONGTEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_bin CHECK (JSON_VALID('{}')));

INSERT INTO t VALUES ('a');

SHOW CREATE TABLE t;

13.1.0-opt>CREATE TABLE t (c LONGTEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_bin CHECK (JSON_VALID('{}')));

Query OK, 0 rows affected (0.009 sec)

13.1.0-opt>INSERT INTO t VALUES ('a');

Query OK, 1 row affected (0.001 sec)

13.1.0-opt>SHOW CREATE TABLE t\G

*************************** 1. row ***************************

       Table: t

Create Table: CREATE TABLE `t` (

  `c` json DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci

1 row in set (0.000 sec)

13.1.0-opt>

--

-- Table structure for table `t`

--

DROP TABLE IF EXISTS `t`;

/*!40101 SET @saved_cs_client     = @@character_set_client */;

/*!40101 SET character_set_client = utf8mb4 */;

CREATE TABLE `t` (

  `c` json DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci;

/*!40101 SET character_set_client = @saved_cs_client */;

--

-- Dumping data for table `t`

--

SET @OLD_AUTOCOMMIT=@@AUTOCOMMIT, @@AUTOCOMMIT=0;

LOCK TABLES `t` WRITE;

/*!40000 ALTER TABLE `t` DISABLE KEYS */;

INSERT INTO `t` VALUES

('a');

/*!40000 ALTER TABLE `t` ENABLE KEYS */;

UNLOCK TABLES;

COMMIT;

SET AUTOCOMMIT=@OLD_AUTOCOMMIT;

/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;

$ /test/mtest/MDEV-38740/MD131026-mariadb-13.1.0-linux-x86_64-opt/bin/mariadb -uroot -S/test/mtest/MDEV-38740/MD131026-mariadb-13.1.0-linux-x86_64-opt/socket.sock test < 1.sql

--------------

INSERT INTO `t` VALUES

('a')

--------------

ERROR 4025 (23000) at line 38: CONSTRAINT `t.c` failed for `test`.`t`