Bitmap increases tif size after reaching a certain point

public void waterMark(string euroPrefix, string resultedTifFolders, string waterMarkedTif)
        {

            using (Brush brush = new SolidBrush(Color.Black))
            {
                using (Font font = new Font("Arial", 50, GraphicsUnit.Pixel))
                {
                    using (Bitmap original_bitmap = new Bitmap(resultedTifFolders))
                    {
                        int compressionTagIndex = Array.IndexOf(original_bitmap.PropertyIdList, 0x103);
                        PropertyItem compressionTag = original_bitmap.PropertyItems[compressionTagIndex];
                        byte[] com = compressionTag.Value;
                        Encoder encoder = Encoder.Compression;
                        EncoderParameters myEncoderParameters = new EncoderParameters(1);
                        EncoderParameter myEncoderParameter = new EncoderParameter(encoder, (long)EncoderValue.CompressionCCITT4);
                        myEncoderParameters.Param[0] = myEncoderParameter;
                        ImageCodecInfo myImageCodecInfo;
                        myImageCodecInfo = GetEncoderInfo("image/tiff");
                        SizeF euroPrefixSize;
                        if (new[] { 5, 7 }.Contains(com[0]))

                        {
                            using (Graphics tempGraphics = Graphics.FromImage(original_bitmap))
                            {
                                euroPrefixSize = tempGraphics.MeasureString(euroPrefix, font);
                            }

                            using (Bitmap new_bitmap = new Bitmap(original_bitmap.Width, original_bitmap.Height + (int)euroPrefixSize.Height + 10))
                            {
                                new_bitmap.SetResolution(original_bitmap.HorizontalResolution,original_bitmap.VerticalResolution);
                                using (Graphics graphics = Graphics.FromImage(new_bitmap))
                                {

                                    graphics.FillRectangle(Brushes.White, 0, 0, original_bitmap.Width, original_bitmap.Height + 100);

                                    graphics.DrawImage(original_bitmap, 0, 0, original_bitmap.Width, original_bitmap.Height);

                                    Point position = new Point(original_bitmap.Width - ((int)euroPrefixSize.Width + 200), original_bitmap.Height + 5);

                                    graphics.DrawString(euroPrefix, font, brush, position);

                                    new_bitmap.Save(waterMarkedTif, /*ImageFormat.Tiff,*/ myImageCodecInfo, myEncoderParameters);


                                    new_bitmap.Save(waterMarkedTif, ImageFormat.Tiff);
                                }
                            }
                            return;
                        }
                        else
                        {

                            Bitmap tempBitmap = new Bitmap(original_bitmap.Width, original_bitmap.Height);

                            using (Graphics tempGraphics = Graphics.FromImage(tempBitmap))
                            {
                                euroPrefixSize = tempGraphics.MeasureString(euroPrefix, font);
                            }
                            tempBitmap = new Bitmap(original_bitmap.Width, original_bitmap.Height + (int)euroPrefixSize.Height + 10);

                            tempBitmap.SetResolution(original_bitmap.HorizontalResolution,original_bitmap.VerticalResolution);

                            using (Graphics graphics = Graphics.FromImage(tempBitmap))
                            {
                                graphics.FillRectangle(Brushes.White, 0, 0, original_bitmap.Width, original_bitmap.Height + 100);

                                graphics.DrawImage(original_bitmap, 0, 0, original_bitmap.Width, original_bitmap.Height);

                                Point position = new Point(original_bitmap.Width - ((int)euroPrefixSize.Width + 200), original_bitmap.Height + 5);

                                graphics.DrawString((euroPrefix), font, brush, position);

                                tempBitmap.Save(waterMarkedTif, ImageFormat.Tiff);
                            }
                        }
                    }
                }
            }
        }