Do the same things happen when it’s the whole group deciding to open the door and get prepared for what might be behind it, or is it just when you open the door while the group is still discussing it? If it’s the same encounters with the whole group, then it’s no problem, they’re already set wncounters. If it’s only when you act alone then your dm is just bad at dming, and you should just resign yourself to waiting around or getting ambushed. Most partys I’ve played in has a leader that makes decisions like that to keep the game moving. Maybe thats what your group needs