If you look at, say, https://download.geofabrik.de/europe/luxembourg.html you'll see a link for "experimental vector tile package conforming to Shortbread schema for use with MapLibre and other MVT capable software".
Seems like they are not available for all regions or countries. E.g. the pages for Europe, Germany and UK don't have such a link.
I guess this is related to data and file size.