[SOLVED] Is this a MySQL bug?

Is this a MySQL bug?

I was running this query against sakila database on MySQL 8.0.17:

select * from film _1 where (
    exists (
        select * from film_actor where (
            select * from (
                select film_id=_1.film_id and actor_id=1
            ) _2
        )
    )
);

This gives 0 results. But if I run this:

select * from film _1 where (
    exists (
        select * from film_actor where (
            select film_id=_1.film_id and actor_id=1
        )
    )
);

I got 19 results, which is expected.

Basically I wrapped the where condition with select * from and suddenly got the wrong result.

To my understanding, wrapping any table value with select * from should give identical result.

I've created this fiddle.

Solution