Hi t01714500930,

Response.ContentType = "image/jpeg";
Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));
Response.BinaryWrite(bytes);
Response.End();

Replace with below code and check.

Response.ContentType = "image/png";
Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));
Response.BinaryWrite(bytes);
Response.Flush()
Response.End();

or try with application/octet-stream ContentType