Windows fog up when the seals around an Insulated Glass Unit fail
The seals let moisture in where it shouldn’t be. Then the moisture turns to fog. And if you’re unfortunate enough not to catch it soon enough, the fogginess becomes a permanent part of your window and thus your home.
Once the seal is broken there is no effective way to re-seal it, and the thermal window almost certainly will begin to get fogged.
And while it may start out as a just barely noticeable smear, it will only get worse with the passing of time. Foggy windows reduce resale value. The broken seals that cause foggy windows make your home more expensive to heat in the winter and cool during the summer. There’s only one way to get rid of fogged windows if they’re stained. You have to replace them.
By replacing the glass unit with a new one you will protect the integrity of your window.