Error when creating a step pane checkout flow

I tried to test it out. I went to add a step pane checkout flow, and got this error.

Fatal error: Declaration of Drupal\Core\DependencyInjection\DependencySerializationTrait::__sleep() must be compatible with Drupal\commerce_checkout\Plugin\Commerce\CheckoutFlow\CheckoutFlowWithPanesBase::__sleep(): array in /web/core/lib/Drupal/Core/DependencyInjection/DependencySerializationTrait.php on line 33

I only get this error when choosing step pane. other checkout flows have no issue.