We cache images in different ways, depending on the rate of requests, no more than 31 days, and most often at least 7 days.

We utilize the proxy cache in nginx to accomplish this, on top of that, Cloudflare caches the most frequently accessed images globally.

Our servers only initiate a refresh when all caches have expired, and only when the image is still being requested by end users.

The rules we use for server-side caching are different from the ones you see in the headers we provide for browsers.