Let me describe the very strange issue I encountered.

Browsing with Chrome 97, the javascript command window.innerWidth always sends me back the same value 1920 but on a given website on which it returns 640.

I've first noticed the issue because website layout was obviously designed for mobile clients.

I've been clearing cache, cookies and storages, closed and reopened browser, but issue remains, specific to that website and on no other.

In private session, problem is also present.

But when I test with other browsers (like Chromium or Firefox) : I don't have the problem.

I don't understand how this can be !