Ventilation vent in the shower stall in the basement

Urgent

Finishing up a basement.

My contractor had used this opening hole (which we suspect was already in existence when the house was built 13 years ago) to vent out the hot water vapour/air from the shower stall in the basement to the exterior of the house.

The shower stall is located in the bathroom which has a toilet and a vanity top/sink

Is there a danger that the hot water vapour would come into contact with the furnace?

What is the seriousness of the problem? **Important Question

To mitigate the problem we will have to ensure that the glass shower does NOT reach to the top of the ceiling as we will have to channel the hot water vapour (from a hot shower) to the other areas in the bathroom (and where else?)

After a bath should I open or close the bathroom door (note the word bathroom door) (Not The Shower Stall Door)?

(The shower stall is custom made and is located inside the complete/whole oblong bathroom).

Will a ceiling exhaust fan mitigate the problem?

The contractor should have created a new vent in the bathroom and far away from the shower stall.

We have already installed and sanded the drywall (but we have not painted the walls)

Is it too late to make the changes (remove the drywall, refit the pipes, re drywall re sand etc etc)?

Is it worth to make the change ?

Thanks