Key error in sign up serializer

Here is the serilializer causing the issue. There is a problem with the create function where the validated data cannot process first_name because it is not validated at the top, but I don’t want it to have a unique validation, so what do I do?

class SignUpSerializer(serializers.Serializer):
    username = serializers.CharField(
        required = True,
        validators = [UniqueValidator(queryset=User.objects.all())]
    email = serializers.CharField(
        required = True,
        validators = [UniqueValidator(queryset=User.objects.all())]
    password = serializers.CharField(write_only = True,required = True,validators=[validate_password])
    password_confirmation = serializers.CharField(write_only = True,required = True)

    class Meta:
        model = User
        fields = ['username', 'first_name', 'last_name', 'email', 'bio', 'preferences', 'password', 'password_confirmation']
        extra_kwargs = {
            'first_name': {'required': True},
            'last_name': {'required': True},
            'preferences': {'required': True}
    def validate(self,data):
        if data['password'] != data['password_confirmation']:
            raise serializers.ValidationError({"password": "Passwords don't match."})
        return data
    def create(self,validated_data):
        user = User.objects.create(
            username = validated_data['username'],
            first_name = validated_data['first_name'],
            last_name = validated_data['last_name'],
            email = validated_data['email'],
            bio = validated_data['bio'],
            preferences = validated_data['preferences']


        return user