TCPDF error: Not a PNG file: https://substackcdn.com/image/fetch/$s_!fUcu!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fa130a0c4-aa66-4943-b64e-7292cec262db_3016x1700.png