The source node in most cases contains the sample message as written by the developer. If it looks like a dot-delimitted string such as "form.label.firstname", then the developer has not provided a default message.

Product: %name%, %sku% %variantCode% is not available and was removed from your %basketType% Product: %name%, %sku% %variantCode% is not available and was removed from your %basketType% key: Product: %name%, %sku% %variantCode% is not available and was removed from your %basketType% Technical information Technical information key: Technical information Collapse all groups Collapse all groups key: collapse_groups|search