EXCEPTION: This browser is not supported or 3rd party cookies and data may be disabled

The domain you're using is deeptent.com, but the domain that firebase is authenticating against and setting cookies from is your .firebaseapp.com domain. So, yes, the cookies are considered third-party. The firebase folks really should take a harder look at how they are connecting custom domains in the firebase hosting setup. Also, see here: Use Google Firebase Authentication without 3rd Party Cookies

I had the same issue with firebase and Angular.

In your environment.ts file, look for:

firebase: {
  authDomain: '<domain>.firebaseapp.com',

And in chrome settings chrome://settings/content/cookies, add the following string to the cookies whitelist:

https://[*.]firebaseapp.com