I have never experienced this with my other cars. But today I noticed condensation on the rear windshield inside of the car. Any insight?

Also, it appears the rear windshield defrost lines (coils?) are missing intermittently. My best guess is that prior to purchasing the car (used), someone had tinted the rear windshield and did a bad job removing the tint, thus causing the defrost lines to come off. I was told I need an entirely need windshield. Is this accurate?

 

As for the condensation, you obviously had a high humidity level inside the car and low temps outside. You didn't leave a steaming cup of coffee in the car overnight, did you?

Someone could have put one of those mobile phone antennas on the rear winsheild. Anyhows, I have tried on other cars to use the "conductive repair paint" (specifically made for defroster elements) they sell at the auto stores to repaint severed defrost lines; I have to say it completely sucks and is a waste of time. The resistance of the paint is soo much higher than the factory lines that it doesn't work well at all.