I copy-pasted them to be able to read them better.

    SELECT
        first_name,
        last_name,
        (
            SELECT MAX(order_total)
            FROM orders
            WHERE customer.id = orders.customer_id
        ) AS maximum_order
    FROM customers;

There's this one to get the maximum order amount for each customer that struck me, and another similar one.

Instead of doing a JOIN they do this weird subquery. You can clearly see that it's the work of an AI and how this AI works (putting together lego pieces which are subqueries), because nobody would be writing this query like that.