Embed image in email with latest C# Sendgrid 9.28.1

I'm trying to embed an image in an email that's send with Sendgrid C# 9.28.1. But somehow the image is not displayed. There is also not a function anymore that's called EmbedImage. Is there a way to do this?

        var client = new SendGridClient(_settings.ApiKey);
        var myMessage = new SendGridMessage();
        myMessage.AddTo(entity.Email);
        myMessage.From = new EmailAddress(_settings.FromAddress, _settings.FromName);
        myMessage.Subject = $"{_settings.FromName} - Image TEST";
        var body = "<div style=\"width:200px;\"><img src=\"cid::IMAGE01\"/></div>" +
                      @"<p>Test message?</p>";

        var attachment = new SendGrid.Helpers.Mail.Attachment
        {
            ContentId = "IMAGE01",
            Content = entity.Base64ImageString,
            Type = "image/png",
            Filename = "image.png"
        };

        myMessage.AddAttachment(attachment);
        myMessage.HtmlContent = body;

        await client.SendEmailAsync(myMessage);