I'm guessing a bug, just because it seems a really odd thing to have just removed if there wasn't something else they wanted to show in its place. It's a handy little feature.

What about stackable items in inventory? Their corresponding circles in the grid change (or changed?) color depending on whether it's a full stack or not. I'm not sure if I've had a full stack of anything since stack sizes were changed from 99 to 999, but now this has me curious. Do those ones still change color? If no-one knows, I'll pick up a full stack of something cheap next time I'm in game and find out.