Symfony version(s) affected: symfony/doctrine-bridge >= 5.1.0

Description
I was updating legacy project to use latest symfony libraries and functional tests have found some issues with one form.
Doing some more in-depth debugging I was able to keep everything working properly by locking DoctrineBridge below 5.1.0.

The issue is that rendered form does not show selected correct values. Values are properly stored in the database when form is submitted (verified in the database). Of course they get cleared when form is resubmitted without selecting those options again.

How to reproduce

Used code to setup the field:

        $builder->add('subscribedUsers', EntityType::class, [
                'class' => User::class,
                'choice_value' => 'id',
                'choice_label' => function(User $user) { return $user->getNameAndSurname(); },
                'required' => false,
                'query_builder' => function (EntityRepository $er) {
                    return $er->createQueryBuilder('u')
                        ->orderBy('u.surname', 'ASC')
                    ;
                },
                'multiple' => true,
            ])
        ;

Example in the rendered view:

Rrelated rows in the database:

Possible Solution

I have found two alternative workarounds for the issue:

1. remove choice_value option completely

Changing choice value to callback like:
'choice_value' => function(User $user) { return $user->getId(); },
does not solve the issue.

Once this option is removed form is rendered correctly:

2. replace query_builder with choices

Example:

'choices' => $this->entityManager->getRepository(User::class)
                        ->createQueryBuilder('u')
                        ->orderBy('u.surname', 'ASC')
                        ->getQuery()->getResult(),

What also seems to solve the issue.

Additional context

This change happened in-between 5.x releases so it seems to be a breaking change. I haven't also found anything related to that in the changelog.

Additionally the issue does not seem to appear in other EntityType fields where multiple option is set to false.