React Native using Expo changed logged in user suddenly - react-native

Question

I'm building a small social media app using React Native, Expo, Redux and firebase.
I created multiple user accounts for testing, i logged in the app using one of them, while i was working on the app, it suddenly changed the user account I logged in with to another user!
Is it normal? If not, what would be the reason for that??
Here's how the registration is being handled:
export class Register extends Component {
constructor(props) {
super(props);
this.state = {
email: '',
password: '',
name: '',
lastname: '',
degree: '',
description:''
}
this.onSignUp = this.onSignUp.bind(this)
}
onSignUp(){
if(
this.state.email != '' &&
this.state.password != '' &&
this.state.name != '' &&
this.state.lastname != ''
){
const { email, password, name, lastname, degree, description } =
this.state;
firebase.auth().createUserWithEmailAndPassword(email, password)
.then((result) => {
firebase.firestore().collection("Doctors")
.doc(firebase.auth().currentUser.uid)
.set({
name,
email,
lastname,
degree,
description
})
console.log(result)
})
.catch((error) => {
console.log(error)
})
}
else{
alert("Make sure you filled all the fields with correct info!");
}
And Here's the App.js
export class App extends Component {
constructor(props) {
super(props)
this.state = {
loaded: false,
}
}
componentDidMount() {
firebase.auth().onAuthStateChanged((user) => {
if (!user) {
this.setState({
loggedIn: false,
loaded: true
})
} else {
this.setState({
loggedIn: true,
loaded: true
})
}
})
}
render() {
const { loggedIn, loaded } = this.state;
if (!loaded) {
return (
<View></View>
)
}
if (!loggedIn) {
return (
<View></View>
);
}
const onAuthStateChangedUnsubscribe =
firebase.auth().onAuthStateChanged(async (user) => {
if (user) {
// -> Alert Email Verification
await user.sendEmailVerification()
const onIdTokenChangedUnsubscribe =
firebase.auth().onIdTokenChanged((user) => {
const unsubscribeSetInterval = setTimeout(() => {
firebase.auth().currentUser.reload();
firebase.auth().currentUser.getIdToken(/* forceRefresh */ true)
}, 10000);
if (user && user.emailVerified) {
clearInterval(unsubscribeSetInterval) //delete interval
onAuthStateChangedUnsubscribe() //unsubscribe onAuthStateChanged
// -> Go to your screnn
return onIdTokenChangedUnsubscribe() //unsubscribe
onIdTokenChanged
}
})
}
})
return (
<View></View>
)
}
}