Does JPA delete items from collection even without Orphan removal= true

Question

I have the below JPA entities defined with bidirectional one-to-many mapping. I observed that delete SQL statement is fired when a comment is removed from a list on post(post.removeComment(...)) even without setting orphan removal = true or making the post reference "null" on the comment .

What is the significance of Orphan removal = true when trying to delete items from a collection in JPA as I see the deletion is working fine even without it.

@Entity(name = "Post")
@Table(name = "post")
public class Post {
 
    @Id
    @GeneratedValue
    private Long id;
 
    private String title;
 
    @OneToMany(
        mappedBy = "post",
        cascade = CascadeType.ALL
    )
    private List<PostComment> comments = new ArrayList<>();
 
    public Post addComment(PostComment comment) {
        comments.add(comment);
        comment.setPost(this);
        return this;
    }
 
    public Post removeComment(PostComment comment) {
        comments.remove(comment);
        return this;
    }
}

@Entity(name = "PostComment")
@Table(name = "post_comment")
public class PostComment {
 
    @Id
    @GeneratedValue
    private Long id;
 
    @ManyToOne(fetch = FetchType.LAZY)
    private Post post;
 
    private String review;
}