api: 'Invalid Date': The timezone could not be found in the database

[sentry-io]

Sentry Issue: ECAMP3-API-45

DateMalformedStringException: Failed to parse time string (Invalid Date) at position 0 (I): The timezone could not be found in the database
  File "/src/Serializer/Denormalizer/InputFilterDenormalizer.php", line 39, in App\Serializer\Denormalizer\InputFilterDenormalizer::denormalize
    return $this->denormalizer->denormalize($data, $type, $format, $context);
  File "/public/index.php", line 5
    require_once dirname(__DIR__).'/vendor/autoload_runtime.php';
...
(20 additional frame(s) were not displayed)

Symfony\Component\Serializer\Exception\NotNormalizableValueException: Failed to parse time string (Invalid Date) at position 0 (I): The timezone could not be found in the database
  File "/src/Serializer/Denormalizer/InputFilterDenormalizer.php", line 39, in App\Serializer\Denormalizer\InputFilterDenormalizer::denormalize
    return $this->denormalizer->denormalize($data, $type, $format, $context);
  File "/public/index.php", line 5
    require_once dirname(__DIR__).'/vendor/autoload_runtime.php';
...
(20 additional frame(s) were not displayed)

Uncaught PHP Exception Symfony\Component\Serializer\Exception\NotNormalizableValueException: "Failed to parse time string (Invalid Date) at position 0 (I): The timezone could not be found in the database" at NotNormalizableValueException.php line 32

not critical, but check if this leads to a 400er or a 500er error