You choose “sign in with a passkey,” then your computer asks for its PIN. It can look as though the website is requesting another password. In the normal passkey flow, the device verification and the website credential play different roles.
The FIDO Alliance’s passkey explanation describes signing in with a credential stored through a device or passkey provider, approved using a familiar device-unlock method such as a PIN or biometrics. That local approval is not the same as typing a reusable website password into the page.
Recognise the prompt you expected
Start from the genuine service and choose its sign-in option deliberately. Read the device or browser prompt, including the account and service shown. Do not give a device PIN to someone in chat or enter it into an ordinary web form because a message calls itself “passkey support.”
A helpful distinction is purpose: the website needs proof that the appropriate credential is being used, while your device needs to verify that you are authorising that use. Seeing a familiar unlock prompt can be part of the intended process; it is not a reason to share the unlock secret with another person.
Know where the passkey lives
Check which provider or device saved it. Some passkeys are synced through a provider; others are tied to particular hardware. The recovery steps and availability on another device depend on that setup. Do not assume that replacing a phone automatically preserves every sign-in method.
Before removing an old device or deleting a credential, verify that you can still access the account through an approved method and understand the service’s recovery process. Keep recovery information protected rather than putting it in a casual note with the account name.
If the sign-in behaves differently from the provider’s documentation, stop and consult the official help route. The useful question is “Which device or provider is approving this credential?” That is more informative than treating every PIN-shaped prompt as the same kind of password request.