[iOS] With 5 bottom tabs, the last bottom tab always pops the stack to top on focus with react-navigation

### Before submitting a new issue

- [x] I tested using the latest version of the library, as the bug might be already fixed.
- [x] I tested using a [supported version](https://github.com/reactwg/react-native-releases/blob/main/docs/support.md) of react native.
- [x] I checked for possible duplicate issues, with possible answers.

### Bug summary

On iOS when having 5 bottom tabs, the last bottom tab always pops the native stack to top when used with react-navigation. This does not occur when using less than 5 tabs. Adding `popToTopOnFocus={false}` to the options does not help. Happens on the latest library version, but also happened on versions `0.4.x`. I'm using Expo SDK 54, react-native 0.81.5. @react-navigation/native 7.1.18.

### Library version

1.0.2

### Environment info

```shell
System:
OS: macOS 15.6.1
CPU: (14) arm64 Apple M4 Pro
Memory: 8.34 GB / 48.00 GB
Shell:
version: "5.9"
path: /bin/zsh
Binaries:
Node:
version: 22.14.0
path: /Users/xxx/.nvm/versions/node/v22.14.0/bin/node
Yarn: Not Found
npm:
version: 10.9.2
path: /Users/xxx/.nvm/versions/node/v22.14.0/bin/npm
Watchman:
version: 2025.09.15.00
path: /opt/homebrew/bin/watchman
Managers:
CocoaPods: Not Found
SDKs:
iOS SDK:
Platforms:
- DriverKit 25.0
- iOS 26.0
- macOS 26.0
- tvOS 26.0
- visionOS 26.0
- watchOS 26.0
Android SDK: Not Found
IDEs:
Android Studio: 2025.1 AI-251.27812.49.2514.14217341
Xcode:
version: 26.0.1/17A400
path: /usr/bin/xcodebuild
Languages:
Java:
version: 17.0.16
path: /usr/bin/javac
Ruby:
version: 2.6.10
path: /usr/bin/ruby
npmPackages:
"@react-native-community/cli":
installed: 20.0.2
wanted: latest
react:
installed: 19.1.0
wanted: 19.1.0
react-native:
installed: 0.81.5
wanted: 0.81.5
react-native-macos: Not Found
npmGlobalPackages:
"*react-native*": Not Found
Android:
hermesEnabled: Not found
newArchEnabled: Not found
iOS:
hermesEnabled: Not found
newArchEnabled: Not found
```

### Steps to reproduce

1) Create a bottom tab navigator with 5 tabs.
2) Make the 5th (last) tab render a native stack with two screens.
3) Navigate in the last tab from its root to a second screen.
4) Switch to any other tab, then switch back to the last tab

Seems to occur on iOS only

### Reproducible sample code

```js
import * as React from 'react';
import { Button, Text, View } from 'react-native';
import { NavigationContainer } from '@react-navigation/native';
import { createNativeStackNavigator } from '@react-navigation/native-stack';
import { createNativeBottomTabNavigator } from '@bottom-tabs/react-navigation';

const Stack = createNativeStackNavigator();
const Tabs = createNativeBottomTabNavigator();

function Screen({ label }: { label: string }) {
return (

{label}

);
}

function MenuHome({ navigation }: any) {
return (

Menu Home
navigation.push('Details')} />

);
}

function Details() {
return (

Details

);
}

function MenuStack() {
return (




);
}

function RootTabs() {
return (

} />
} />
} />
} />
{/* IMPORTANT: Last tab renders a native stack */}


);
}

export default function App() {
return (



);
}
```

Start with the supplied reproduction using createNativeBottomTabNavigator, a five-tab navigator, and a native stack in the final tab; run it on iOS and compare behavior with fewer tabs. Trace tab focus and stack restoration around the final tab, then verify that returning to it preserves the Details screen without popping to the root.

索引モデルが issue の本文から書いたものです。