I know that previous versions colored the entire trim of a drawer based on the size upgrade applied, but now that upgrades stack it has been removed. That said, I really like the idea of knowing which drawers I have put upgrades into and how many. Would it be possible to have the upgrade indicators display similar to the void upgrade does? That way it could just be a column of indicators. And since there are only a few slots, I don't think it would get overly cluttered. If it were a concern, maybe have a config option to toggle the behavior?

Here's a mockup of how I think it could look.

I guess I could take a crack at it. I've been missing the old colored upgrade trim for a while, even as obtrusive as it was.

(I started adding these indicators even before I saw your mockup. Great minds think alike!)

Yeah wow those look great, thanks again @chimericdream