So pretty much solved the mystery.
Perhaps this may be helpful to someone else.

If you look at the layout plan of my apartment, you'll see that the area by my front door, which is about 2 yards by 2 yards, is where both my intake and exhaust are placed, because the opposite wall is full of water pipes and shit.

This area has been boxing in and containing the warm air from the exhaust apparently, so the intake air has been around 28C.
Thats all it took to muck everything up, and it took quite a few days of headscratching to work out.

With a window cracked open all the time now keeping ambient temps cool, I have no issues with heat anymore. Going to try putting a fan in my hallway to just create a better glow of the warm air into my living room, see what happens.