When I print my drawing as PDF, my furniture drawing has few line weight is heavy than others. I use the same layer, but it still comes with heavier line than others. I attached two images of the issue.
There are several reasons this could be occurring. there are similar colors that might not be clear when you view your file in model space make sure your line is of a color that’s set to a line thickness. There are also overrides for elements that are blocks or groups check that the line is set to print lineweight as layer color.