keychain missing from iCloud settings

Can anyone help me?

I recently got a 13 Pro upgraded from an 8 plus, I’ve successfully transferred all data from the 8’s iCloud backup.

But the Keychain menu is missing as you can see here:

I didn’t changed anything from the setting prior to backing up, I force restart, reset settings, even erasing and restore again but still that Keychain is missing.

I’ve followed the steps from this guide:

, still no good.

I didn’t turn off the two-factor authentication, as you can see:

I’m running on iOS 15.4, and still puzzled.

Glad if anyone can help.