TYPO3 Testing Framework - FunctionalTestCase not loading TCA overrides from extension

How can I apply TCA overrides in a FunctionalTestCase class?

I am writing a TYPO3 functional test for an extension that extends the FrontendUser domain model and repository. The TYPO3 testing framework is used to run the test but it does not seem to load the override TCAs from the Configuration/TCA/Overrides/fe_users.php file. Is there a Bootstrap function I am missing or perhaps extra setup? (Anything below in < > tags has been replaced for NDA purposes, such as internal extension keys)

This is the error:

   ┐
   ├ TYPO3\CMS\Extbase\Persistence\Generic\Storage\Exception\SqlErrorException: Unknown column 'gender' in 'field list'
   │
   ╵ <extension-folder>/.Build/Web/typo3/sysext/extbase/Classes/Persistence/Generic/Storage/Typo3DbBackend.php:146
   ╵ <extension-folder>/.Build/Web/typo3/sysext/extbase/Classes/Persistence/Generic/Backend.php:634
   ╵ <extension-folder>/.Build/Web/typo3/sysext/extbase/Classes/Persistence/Generic/Backend.php:282
   ╵ <extension-folder>/.Build/Web/typo3/sysext/extbase/Classes/Persistence/Generic/Backend.php:269
   ╵ <extension-folder>/.Build/Web/typo3/sysext/extbase/Classes/Persistence/Generic/PersistenceManager.php:166
   ╵ <extension-folder>/Tests/Functional/Domain/Repository/FrontendUserRepositoryTest.php:96
   ┴

This is the functional test class:

class FrontendUserRepositoryTest extends FunctionalTestCase
{

    protected $testExtensionsToLoad = [
        'typo3conf/ext/<my-extension-key>'
    ];

    protected $coreExtensionsToLoad = [
        'typo3/sysext/extbase'
    ];

    /**
     * @var FrontendUserRepository
     */
    protected $frontendUserRepository;

    /**
     * @var PersistenceManager
     */
    protected $persistenceManager;

    /**
     * @var FrontendUser
     */
    protected $frontendUser;

    /**
     * @var string
     */
    protected $email;

    /**
     * @var string
     */
    protected $firstName;

    /**
     * @var string
     */
    protected $lastName;

    protected function setUp(): void
    {
        parent::setUp();

        Bootstrap::initializeBackendUser();
        $GLOBALS['BE_USER']->user['admin'] = 1;
        $GLOBALS['BE_USER']->user['uid'] = 1;
        $GLOBALS['BE_USER']->workspace = 0;
        Bootstrap::initializeLanguageObject();

        /** @var PersistenceManager $persistenceManager */
        $this->persistenceManager = GeneralUtility::makeInstance(PersistenceManager::class);

        $objectContainer = new Container($this->getContainer());
        $objectManager = new ObjectManager($this->getContainer(), $objectContainer);
        $this->frontendUserRepository = new FrontendUserRepository($objectManager);
        $this->frontendUserRepository->injectPersistenceManager($this->persistenceManager);


        $this->email = 'test@test.com';
        $this->firstName = 'Tester';
        $this->lastName = 'Man';

        $this->frontendUser = GeneralUtility::makeInstance(FrontendUser::class);
        $this->frontendUser->setEmail($this->email);
        $this->frontendUser->setFirstName($this->firstName);
        $this->frontendUser->setLastName($this->lastName);
    }

    /**
     * @test
     * @throws \TYPO3\CMS\Extbase\Persistence\Exception\IllegalObjectTypeException
     */
    public function testRetrieveByEmailFromRepository()
    {
        $this->frontendUserRepository->add($this->frontendUser);
        $this->persistenceManager->persistAll();

        /** @var FrontendUser $frontendUser */
        $frontendUser = $this->frontendUserRepository->findUserByEmail($this->email)->getFirst();
        $this->assertEquals($this->email, $frontendUser->getEmail());
        $this->assertEquals($this->firstName, $frontendUser->getFirstName());
        $this->assertEquals($this->lastName, $frontendUser->getLastName());
    }

    /**
     * @test
     */
    public function checkIfTableExists()
    {
        $queryBuilder = $this->getConnectionPool()->getQueryBuilderForTable('INFORMATION_SCHEMA.COLUMNS');
        $queryBuilder->getRestrictions()->removeAll();
        $query = $queryBuilder->select('COLUMN_NAME')
            ->from('INFORMATION_SCHEMA.COLUMNS')
            ->where(
                $queryBuilder->expr()->eq('TABLE_NAME', $queryBuilder->createNamedParameter('fe_users'))
            )
            ->execute();

        /* Dumps the base fe_users table columns without the TCA overrides applied */
        var_dump($query->fetchAllAssociative()); 
    }

}