Please, refer to this Repository that contains a project that reproduces the problem:
https://github.com/Andremoniy/hibernate-6-order-by-issue

Basically, under certain conditions the column name provided in the OrderBy annotation is not transformed to the physical name of the column in the databse.

This is a combination of the three different conditions:

1. The field used in the OrderBy should be a part of a composite key on the mapped entity. In our case this is DepartmentId composite key:

public class DepartmentId implements Serializable {

    private Company company;
    private String departmentCode;

}

1. The field used in the OrderBy entity should contain more than a word in its name (if we rename departmentCode into code, the issue goes away).
2. There should be an HQL query that uses LEFT JOIN FETCH on the problematic entity.

@Query("""
            SELECT c 
            FROM Company c 
            LEFT JOIN FETCH c.departments 
            WHERE c.name = :name
            """
    )
    Optional<Company> findCompanyByName(@Param("name") String name);