Cloudflare not respecting Cache-Control

Question

I have an express web server that servers super-dynamic images.

The images then go on to be hosted on other websites, which use cloudflare.

On my site, the images are dynamic, like I want, and reload every single time the page loads.

Here are the routes:

app.get("/comments/:id.:ext",(req, res, next) => {
    res.setHeader('Cache-Control', 'no-store');
    res.setHeader('Surrogate-Control', 'no-store');
    res.setHeader('Pragma', 'no-cache');
    res.setHeader('Expires', '0');
    next();
}, imageRoute);
app.get("/comments/:id", (req, res, next) => {
    res.setHeader('Cache-Control', 'no-store');
    res.setHeader('Surrogate-Control', 'no-store');
    res.setHeader('Pragma', 'no-cache');
    res.setHeader('Expires', '0');
    next();
}, imageRoute);

Cloudflare docs says

Cloudflare does not cache the resource when:

    The Cache-Control header is set to private, no-store, no-cache, or max-age=0.
    The Set-Cookie header exists.

But, on the host website (replit.com, for reference), the images take hours to update.

They seem to be hosted on a CDN...

Here is a link to an example image: https://replit.com/cdn-cgi/image/quality=80,metadata=copyright,format=auto/https://image-comments.sojs.dev/comments/14.png The original url is https://image-comments.sojs.dev/comments/14.png.

That URL is never cached.

For reference:

I do not understand why my headers are being ignored.

Any help appreciated