Visiting my website with an URL suffix shows an outdated website

I have a custom domain called my_company.ai and an apex CNAME with target comp.pages.dev.

Everything is configured so that when visiting my_company.ai in any web browser, it is redirected to https://www.my_company.ai which seems to conform to comp.pages.dev.

The issue arises when visiting my_company.ai/something: it shows an outdated webpage, that may not even be an old version of comp.pages.dev/something.

Why and how to solve this?

Are you sure your browser is not simply using cached resources? (Shift+F5)