This custom middleware can be used to overwrite the schema manager on the connection. It allows for supporting DATETIME(6) (with precision) to be properly detected by Doctrine. See https://github.com/doctrine/dbal/issues/6631

DoctrineSchemaUpdateMiddleware

final readonly class DoctrineSchemaUpdateMiddleware implements Middleware
{
    #[Override]
    public function wrap(DriverInterface $driver) : DriverInterface
    {
        return new class($driver) extends AbstractDriverMiddleware {
            #[Override]
            public function getDatabasePlatform(ServerVersionProvider $versionProvider) : AbstractPlatform
            {
                $platform = parent::getDatabasePlatform($versionProvider);

                // We want this to break whenever we upgrade to a newer MySQL verion or whenever
                // Doctrine DBAL removes the deprecated MySQL80Platform class.
                Assert::true($platform::class === MySQL80Platform::class);

                return new class extends MySQL80Platform {
                    #[Override]
                    public function createSchemaManager(Connection $connection) : MySQLSchemaManager
                    {
                        return new class($connection, $this) extends MySQLSchemaManager {
                            #[Override]
                            protected function _getPortableTableColumnDefinition(array $tableColumn) : Column
                            {
                                $column = parent::_getPortableTableColumnDefinition($tableColumn);

                                if ($tableColumn['type'] === 'datetime(6)') {
                                    $column->setType(Type::getTypeRegistry()->get('utc_microdatetime_immutable'));
                                } elseif ($tableColumn['type'] === 'timestamp' && $tableColumn['EXTRA'] === 'on update CURRENT_TIMESTAMP') {
                                    $column->setType(Type::getTypeRegistry()->get('timestamped'));
                                }

                                return $column;
                            }
                        };
                    }
                };
            }
        };
    }
}

Where did you plug it in?
I am using DBAL for diff only and trying to create migrations between two shemas.
No framework - just plain PHP with connections to two databases.
Any pointers?

Something like this:

$b = new \Doctrine\DBAL\Configuration();
$b->setMiddlewares([new DoctrineSchemaUpdateMiddleware()]);