The 1080p Ceiling
Instagram's CDN is built for speed. Every image you upload is aggressively downsampled to a maximum width of 1080 pixels and converted to a highly compressed JPEG. This reduces file sizes by up to 90%.
While this is great for scrolling on a bus, it's terrible for your digital portfolio. By using an external downloader, you can often access the least-compressed version of that 1080p file that Instagram stores for its high-DPI displays.