"sv" unexpectedly appearing in FieldDefinition.Localizations

In my environment, I use the “sv-SE” and “en-US” cultures for product fields. When I process all the FieldDefinitions to extract the various localizations in FieldDefinition.Localizations though, I find “sv-SE” and “en-US” as expected, but also “sv”. Why is this?

Litium version: 7.1.0

Some of the field have got information for the culture sv, maybe an integration.