Probably just other usages of "im Urlaub" greater, like "im Urlaub erlebten wir das und das", "im Urlaub hatten wir schönes Wetter" and so on. "In Urlaub" as in by now being there, appears entirely wrong in Upper-Austrian, but I don't find out about the Germans. I've also heard about https://bihlmayermedia-bilder.com/urlaub/wir-sind-im-urlaub/