TCPDF error: Not a PNG file: https://substackcdn.com/image/fetch/$s_!RPUu!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1f63ff74-dd4d-437d-84b1-b0c7f00fb7fa_2250x1669.png