Perhaps Just other usages of "im Urlaub" amplified, like "im Urlaub erlebten wir das und das", "im Urlaub hatten wir schönes Wetter" and so forth. "In Urlaub" as in currently staying there, appears wholly Erroneous in Upper-Austrian, but I do not know about the Germans. I have also heard about https://bihlmayermedia-bilder.com/urlaub/wir-sind-im-urlaub/