When it comes to passkeys, Hybrid Mode can take place when the same device is using two different browsers to authenticate.
Since the keys are not shared between browsers, you'll be prompted to authenticate another way and a QR code from the browser will be shown to the user.
The general flow for this mode is the following:
1. Using the first browser, you supply your identifier and authenticate using a passkey.
Browser prompt to use Passkey.
Prompt from browser to use Passkey saved in another device.
2. Then, in another browser, you supply the same identifier and attempt to authenticate using a passkey.
View From Device with Passkey