FK constraints on versioned tables use historical rows, which may cause constraint violation

create or replace table t1 (a int, key(a)) with system versioning;

create or replace table t2 (b int, foreign key (b) references t1(a));

insert into t1 values (1),(2);

insert into t2 values (1);

delete from t1 where a = 1;

alter table t1 drop system versioning;

MariaDB [test]> delete from t1 where a = 1;

Query OK, 1 row affected (0.07 sec)

MariaDB [test]> select * from t1;

+------+

| a    |

+------+

|    2 |

+------+

1 row in set (0.00 sec)

MariaDB [test]> select * from t2;

+------+

| b    |

+------+

|    1 |

+------+

1 row in set (0.00 sec)

MariaDB [test]> select * from t1 for system_time all;

+------+

| a    |

+------+

|    1 |

|    2 |

+------+

2 rows in set (0.00 sec)

MariaDB [test]> alter table t1 drop system versioning;

Query OK, 1 row affected (1.29 sec)

Records: 1  Duplicates: 0  Warnings: 0

MariaDB [test]> select * from t1;

+------+

| a    |

+------+

|    2 |

+------+

1 row in set (0.00 sec)

MariaDB [test]> select * from t2;

+------+

| b    |

+------+

|    1 |

+------+

1 row in set (0.00 sec)