Firebase auth: Operation timeout issues on login, using social media login eg. google

### [REQUIRED] Describe your environment
* Operating System version: Windows 10
* Browser version: Chrome
* Firebase SDK version: 7.19.1
* Firebase Product: auth

### [REQUIRED] Describe the problem
We are using firebase on webapp which acts as an SSO provider for our connected applications, deployed on appengine.
At times, after we enter the credentials for social media login eg. google, it doesn't move ahead and gets stuck, **giving operation time out error.**
When we inspected on console, we could see the error with iframewrapper.js which is part of the highlighted javascript.(iframewrapper.js)
**Even though having good network bandwidth, many users are facing this issue they are able to login only after multiple retries.**
**What is the probable cause for this issue and solution?
Is this issue resolved post 7.19.1 Firebase release? We have continuously updated the versions from 7.13.2 till 7.19.1.**
We could see many issues logged on various forums regarding operation time out, but we couldn't get satisfactory resolution till date.

#### Steps to reproduce:
1) Go to sso sign in page
2) Click on social media login option eg. google
3) Enter credentials
4) It comes back to sso sign in page giving operation time out error on google icon

Attaching screenshot for reference:
Screenshot 1:

Screenshot2:

Start with the reported social-login flow in Firebase SDK 7.19.1 and inspect the referenced iframewrapper.js error after Google credentials are submitted. Reproduce the timeout from the listed SSO sign-in steps and compare behavior across the reported versions; done would require identifying a reproducible cause and documenting or validating a resolution.

Written by the indexing model from the issue text.