ChoiceType group_by not honored after dependency change

[craigh]

I have something like

            $builder->addDependent(
                'foo',
                'bar',
                function (DependentField $field, ?Bar $bar) {
                    if ($bar === 'blue') {
                        $field->add(EntityType::class, [
                            'class' => Baz::class,
                            'group_by' => function (Baz $baz) {
                                return $baz->isPublic() ? 'Public' : 'Private';
                            },
                            'choices' => $bar->getBazChoices(),
                            'choice_label' => 'name',
                        ]);
                    }
                }
            );

On the first load, the choices are grouped properly, but when the parent field changes and triggers change to the dependency, the group_by option is no longer honored.