Firebase Auth systems stopped working after signOut - flutter

Question

I was making a profile page. I also added a "Logout" button to the profile page.
The codes are as follows:
InkWell(
child: ListView(
shrinkWrap: true,
children: [
ListTile(
leading: Icon(Icons.person, color: Colors.black,),
title: Text("Profile", style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold, color: Colors.black),),
onTap: () {
//Navigator.push(context, MaterialPageRoute(builder: (context) => profileScreen()));
},
),
ListTile(
leading: Icon(Icons.settings, color: Colors.black,),
title: Text("Settings", style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold, color: Colors.black),),
onTap: () {
//Navigator.push(context, MaterialPageRoute(builder: (context) => settingsScreen()));
},
),
ListTile(
leading: Icon(Icons.exit_to_app, color: Colors.black,),
title: Text("Logout", style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold, color: Colors.black),),
onTap: () {
FirebaseAuth.instance.signOut(); // !!!!!!!!!!!!<<<<<<<
},
),
],
),
onTap: () {
print("clicked");
},
),
Console:
W/System (31904): Ignoring header X-Firebase-Locale because its value was null.
When I press the ListTile with "Logout" written FirebaseAuth.instance.signOut(); the code would work. I pressed it and my access to the account was cut off. It also gave a few errors but those errors were normal errors anyway.
Then I tried to login to the account again, I couldn't. It gave an error other than password and email errors.
Apart from these, functions such as registration and forgot password do not work.
What could have caused this problem? How can I solve it? Thanks in advance for your help.