That's a once type thing, the website is supposed to prompt you after that QR login whether you'd like to enroll your local authenticator (Chrome, Edge, Firefox,etc) after you login so you don't need to keep using the QR code.
The concept is that many people will frequently have multiple passkeys, thus not be 'locked in' to any one sync ecosystem.
> When signing in on a different computer, either the credential will already be locally present (if the computer is using the same sync fabric as the phone) and suggested by autocomplete, or else the user’s phone can be used to transmit the assertion to the computer. In the latter case, the service may invite the user to enroll a local platform authenticator for easier sign-in in the future. (Now the newly registered credential may be part of a different sync fabric, and thus enable local sign-in on other devices.)
The concept is that many people will frequently have multiple passkeys, thus not be 'locked in' to any one sync ecosystem.
From https://github.com/w3c/webauthn/wiki/Explainer:-broadening-t...
> When signing in on a different computer, either the credential will already be locally present (if the computer is using the same sync fabric as the phone) and suggested by autocomplete, or else the user’s phone can be used to transmit the assertion to the computer. In the latter case, the service may invite the user to enroll a local platform authenticator for easier sign-in in the future. (Now the newly registered credential may be part of a different sync fabric, and thus enable local sign-in on other devices.)