Why does www.icloud.com always ask for verification?

Every Sunday I log on to https://www.icloud.com.
For a while now, I get the screen asking for my Two-Factor Authentication.
It says “A message with a verification code has been sent to your devices. Enter the code to continue.

Every time, I click on “Didn’t get a verification code?”
I select Text Me.
I get the text message, and enter the code and get on. I tell it to trust this device and browser.

Why don't I get the initial verification code?

Why does it not remember that I told it to trust the browser?

What can I do to get it to remember?