signInWithRedirect question

### Operating System

ios

### Browser Version

safari 16

### Firebase SDK Version

10.7.2

### Firebase SDK Product:

Auth

### Describe your project's tooling

react app in web

### Describe the problem

I tried using nginx reverse proxy to solve the problem of using the signInWithRedirect method to obtain authentication results on certain browsers that disable third-party cookies. I configured the following code in nginx and added it to the redirect list in the Google service backend https://customdomain.com/__/auth/handler Then I changed my authdomain to customdomain.com in the code, but when I redeployed my React Spa project, I found that the login redirect path changed to https://customdomain.com/__/auth/handler?xxx=yyy This is normal, but the page stays here and it does not redirect to https://accounts.google.com/

Forwarding https://customdomain.com/__/auth/handler -- to --> https://project.firebaseapp.com/__/auth/handler

nginx example config:

```
location /__/auth {
# Firebase Auth Helper Proxy Forwarding Config

allow all;

proxy_http_version 1.1;
proxy_pass https://.firebaseapp.com;
}
```

### Steps and code to reproduce issue

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