Jaguar rear window blurry

My father-in-law owns a 2000-era Jag S-type that he has parked in his driveway in central Florida for many years. The rear window, which has wires embedded in it (rear windor defogger? radio antenna?) has become extremely blurry - to the point where it’s a safety hazard. This is the original equipment - no aftermarket tinting or anything applied. Is this a defect, or something that just happens after years in the Florida heat and sunlight? Can it be fixed inexpensively?

Are you SURE there is no tinting film on it? That rear glass is tempered as is all rear car glass since the '50s. I’ve never seen any of it degrade.

Perhaps it needs an extensive cleaning from deposits built up over the years. Any smoking done in the car?

Convertible or hard top?

Thanks - nothing aftermarket. If Jaguar applies rear window defogger or radio antenna wires with a film, I suppose that could be the culprit. But I’ve never seen a similar problem on any other vehicle I’ve owned with rear window wires.

Hard top

No smoking. My father-in-law is a non-smoker and did not allow smoking in his car. We’ve tried to clean the window with several window cleaning agents to no avail. The window remains cloudy.