If you are using ShortPixel Image Optimizer and Cloudflare, and you get 503 errors when trying to optimize an image, it is possible that all you need to do is whitelist our IPs on Cloudflare’s control panel.
You can also confirm that by opening your image URLs from an Incognito/Private window. If you see the following it means you have DDoS protection enabled from Cloudflare and that’s why ShortPixel’s servers cannot access the images to optimize.
To learn more about how to properly configure Cloudflare to work with SPIO, click here.