Another issue on the lever nuts is clearly visible on the large image of them which @ngreen posted, and which I learned at Rock City as a result of power problems. Go back and look.
— You’ve scolled back up and looked, at ngreen’s first image and evaluated it against the OP, didn’t you? —
Yup, 20A. Don’t use these things behind 30A or 40A breakers, which was OP’s question. I don’t recall exactly how, but stuff was melted and stuff was carbonized. As strange as it sounds, I apologized to the team in question for the inspection team having missed this and passed their inspection. As 3011 is a particularly gracious team, they then and there swore off those lever nuts for 30A and 40A circuits, forgave the inspectors, and moved on!