What is the reason for the "content script" to not execute?

Question

Read the chrome extension docs, but my mental model must be wrong. I can't understand the reason why "content.js" doesn't execute below.

I have got this manifest.json:

{
    "manifest_version": 3,
    "name": "Foo",
    "version": "1.0.0",
 
    "content_scripts": [
        {
            "matches": ["https://*.twitter.com/*"],
            "js": ["content.js"]
        }
    ]
}

And the content.js

alert("foo")

When I go to "https://twitter.com", I see the alert "foo".

But if I click to see another profile within the twitter like https://mobile.twitter.com/FlutterDev, I don't see the alert "foo".

I checked and see that content.js is loaded but not executed. What am I missing in my mental model, please?

Thank you,