> Purging the cache
> If Page Rules or other cache settings are used on your custom domain, that may lead to stale assets being served after a new build. You can resolve this by selecting Caching > Configuration > Purge Everything in the dashboard to ensure the latest build gets served.

Custom domains · Cloudflare Pages docs
https://developers.cloudflare.com/pages/platform/custom-domains/

deployした時にこのAPI叩く？

Cloudflare API Documentation
https://developers.cloudflare.com/api/operations/zone-purge-files-by-cache-tags,-host,-or-prefix