I suspect it either got deprecated or there are internal changes at geohub. There’s another map at https://geohub.gov.si/ags/rest/services/TEMELJNE_KARTE/LIDAR202325CVAT/MapServer/WMTS/1.0.0/WMTSCapabilities.xml that seems to serve the same purpose. It’s licensed under CC-BY 4.0 with attribution: ZRC SAZU, Inštitut za antropološke in prostorske študije