Logging in with Google doesn't work without third party cookies

[lsl]

We use a google library to handle google sign in and it doesn't support third-party-cookie-free operation. It seems like this is a won't fix issue.

I'm creating this issue to track further investigation and hopefully find a workaround / alternative approach.

Secondary issue: need to confirm that a user can login using a password reset if they've only ever logged in with google auth. Confirmed, password reset is an available workaround if required.

We load the google-api-javascript-client with a loadScript call, and catch this specific error gracefully. With 3rd party cookies going away this will be the default mode of operation. I think we'll either need to change to oauth or remove the feature as continuing to suggest users disable 3pc is not really an option for mass use.

It would be good if someone can confirm they can repro this as I couldn't see this error in the e2e test logs for #52407 but the error does show up for me locally.

Steps to reproduce the behavior

Disable third party cookies for your browser (e.g. chrome incognito) and attempt to login with a Google account.

https://wordpress.com/log-in

What I expected to happen

Being able to login

What actually happened

The login option is disabled with some info text explaining you need to enable third party cookies.

There is a console error:

{error: "idpiframe_initialization_failed", details: "sessionStorage is not available in the current environment."}

Screenshot

[niranjan-uma-shankar]

Props @aneeshd16 for finding this but the Google sign-in works on Safari even with 3rd party cookies blocked.
This issue is however seen on Chrome and Firefox.