Good news for those who were subscribed to the #GNOME releases/development schedule using #GNOMECalendar or
@EvolutionGnomeGNOME Evolution: as per https://gitlab.gnome.org/Teams/Websites/release.gnome.org/-/issues/55, the calendar HTTP and webcal links on https://release.gnome.org/calendar/ have been fixed today.
Those calendars now officially live on that subdomain, so you may want to update the subscription URLs in your app.