Hello wwwouaiebe,

This is a known bug in osm-carto, there is a pending pull request aimed at solving it once and for all.
https://github.com/gravitystorm/openstreetmap-carto/pull/4797

Most other layers, e.g. ÖPNVKarte, Transport Layer or ORM can perfectly show railway platforms that have the covered=yes tag.  But I agree with you that a newbie who believes that OpenStreetMap is just the default map style will have a hard time until this rendering bug is solved.