There's a bug that, when you make exits and preview your game, the X and Y axes of the exits will get messed up/the game will add duplicate exits.
This makes your character transport to weird places!
According to a thread in the bitsy community, it is a bug that started on 7/7/23. There's a merge request with a fix, but it's waiting on approval. Meaning it's still broken at the moment.
If you are experiencing problems right now, there is a hotfix.
Via user peabodyman:
Open the dev tools in your browser, navigate to the Console and copy and paste this:
function createExitData(x, y, destRoom, destX, destY, transition, dlg) {
return {
x: x,
y: y,
dest: {
room: destRoom,
x: destX,
y: destY
},
transition_effect: transition,
dlg: dlg,
};
}
I was having issues and this fixed them.
I hope my time and headache saves you time and headache. 
