Invisible auto_increment vs LAST_INSERT_ID

gistfile1.txt

mysql80 15> SHOW CREATE TABLE t1\G
*************************** 1. row ***************************
       Table: t1
Create Table: CREATE TABLE `t1` (
  `num` bigint unsigned NOT NULL AUTO_INCREMENT /*!80023 INVISIBLE */,
  `val` varchar(32) COLLATE utf8mb4_ja_0900_as_cs DEFAULT NULL,
  UNIQUE KEY `num` (`num`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_ja_0900_as_cs
1 row in set (0.00 sec)

mysql80 15>
mysql80 15>
mysql80 15>
mysql80 15> INSERT INTO t1 VALUES ('one');
Query OK, 1 row affected (0.01 sec)

mysql80 15> SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                1 |
+------------------+
1 row in set (0.00 sec)

mysql80 15> INSERT INTO t1 VALUES ('two');
Query OK, 1 row affected (0.00 sec)

mysql80 15> SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                2 |
+------------------+
1 row in set (0.00 sec)