It is a valid concern. But with reasonable precautions, limiting use time, never leaving it running unattended, and maintaining adequate ventilation it isn't really much of a risk.

In some ways propane, along with other pressurized gas units, have an advantage in this because they are quite easy to relight. So there is less temptation to leave them going to avoid having to follow an elaborate procedure to restart them once they cool.

It also helps that the local climate is fairly warm compared to the northern states, even in winter, so there is less resistance to opening a window a bit.

I have made it many years with only moderate brain damage. YMMV.