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 already currently being there, appears totally Incorrect in Higher-Austrian, but I don't find out about the Germans. I have also heard https://bihlmayermedia-bilder.com/urlaub/wir-sind-im-urlaub/