This is a common issue in Shopify and it is connected to so-called API limits on your Shopify Plan, something many merchants are not aware of: https://shopify.dev/api/usage/rate-limits.

After the limit is reached for a store, Shopify informs us (and any other App) that no more requests can be made for your store at the moment.

This results in an issue with your order, and it could happen if an order contains a lot of items. In cases like this one, this will usually get resolved by contacting Shopify's support team. By increasing the API limit for your store, errors should be prevented. If you notice this error, feel free to message us and we will resolve this for you.