They also recommend removing the Glowforge from the external venting to prevent inflow of exterior conditions directly to the machine – though the way mine is set up, this is a bit of a pain.
I tend to leave my lid a bit open instead, to allow interior air to circulate in. My vent is louvered, so there isn’t going to be much backflow, but it’s been below freezing lately, so better safe than sorry.
EDIT: Don’t want this: