Welcome to Mayo Connect. If you use the search function (magnifying glass) and search for ground glass opacities (or GGO) you will find it has been discussed a number of times.
It really sounds scary, but it is just a descriptive term used by the radiologist to describe their findings on an image. What it means is that there is a cloudy or indistinct area where they don't see a specific artifact like a nodule or a cavity, but it also isn't nice and clear. The radiologist may or may not have access to your full medical record, and may or may not know exactly what the ordering doc is looking for. So they describe it in terms the doc knows, and leave it to them to make a final diagnosis. Or, if the radiologist sees something concerning and significant, the may add a note to the doc like "suggestive of bronchiectasis" or "possible infectious cavity"
Typically, it comes after a respiratory infection, where mucus and possibly some cells have gathered, and as the lung recovers the opacity disappears. Other times it can be a sign of an ongoing and possibly undiagnosed infection or of disease.
Unless there is evidence or history of cancer or infection, or a serious underlying lung disease, the plan is usually wait and watch - like repeating your image in 6 months.

So it is not that the radiologist or physician doesn't know - it is more usually that it's just something to keep an eye on. If, on the other hand, the suspect something serious, they do more imaging, blood tests, a biopsy...

Did you recently have a respiratory infection or Covid? Or do you have a history of asthma, COPD or emphysema?
Sue