How can you fix cloudy privacy glass?

My rear window in my van, which has defroster wires in it, has become quite blurry, as it if isn’t attached to the glass as smoothly as it was. Anyone know how to fix this? It seems to be getting worse, so that now I can see headlights behind me at night but can’t even tell if it’s a semi or a Honda….. Can’t afford a pro, so grateful for any hints. thanks for your time