hmmm - I don't know if I see what you mean - there is a line on the foliage - that's where the leaf will fall off - the lower portion will remain for some time after that.
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As far as the line you can see across the base of the leaves then this is perfectly normal and is called the abscission layer. As the leaves age they die off and break away from the plant along this line.
Correct observation and totally normal. Some plants show a more definite delineation than others but all Cyms have it. When the leaves of the older Pseudobulbs die, they will all break at this point, and the remaining sheaths will turn brown and stay around the BB until physically removed.
All of my cymbidiums have always had those lines (abscission layer) across the lower part of the leaves, even on new growth. It is where the leaf will eventually drop off after it dies. I am happy to learn the name of that part of the plant. The pseudobulb will stay green for a long time (years) after the leaves fall off and provide some food for the plant.