I'm hardly using my car and barely drove 30 miles in the last 3 weeks or so, and I've noticed a 12-mile drop in the estimated range during that period.
My car has always had very close to 279m of the range displayed at 90% SOC. My usage pattern would use ~80% of the battery once a week and ~20% of the battery on other days. Nothing else changed except for the drastic drop in usage, and there is absolutely no reason to contemplate battery deterioration for the drop in estimated mileage.
I think this situation showcases the relationship between usage patterns and estimated mileage nicely. This relationship was always discussed on the forum, and I'm convinced about it with the observations in my own car.