text: Hey Martin868,
  
  It takes a long time for OSM Carto (the default map style) to update objects visible on lower zooms aka larger or more complex objects such as boundary relations. Slower updates are somewhat intentional as well as to prevent displaying vandalism. Though, if a coastline relation is broken, you may occasionally see a country or continent flooded.
  This is not something which can be fixed by changing OSM data.
  
  I hope this answers your questions.