The nectar flow had stopped in my locale around 10 days ago. I could see bees robbing. Since then, the robbing has stopped as the nectar flow was going again. I don't think the bees are putting up a lot of honey, but there is something out there still for them.
White and Yellow sweet clover have waned and are pretty much done. The late summer flowers are in play right now. Purple Loosestrife, Spotted Knapweed, Joe Pyeweed. There are other perennials blooming that are giving up some nectar. We should see Goldenrod blooming soon. So there still be some nectar still to be had.
I wouldn't put anymore supers on if the bees are still capping honey in the current supers that are already on the hive.
In the big picture the honey season is over for many of us. Beekeepers need to switch their attention to mite treatments. Don't wait too long to do mite treatments. Mites can start damaging your bees soon. Later next week the temperatures look good for using Formic Acid. I have made a post about this a couple posts ago. By waiting too long to treat for mite can put your colony in peril for winter survival. Please look at that post if you are considering Formic Acid as a mite treatment.