It was possible in GoodNotes 4 to draw very thin lines, 1 pixel size.
I often use GoodNotes by beginning to write something on one sheet with the stylus, then select all and reduce the size, then zoom in to write more things on the page.
On GoodNotes 4 the smallest width (0.5) was the same when reducing.
On GoodNotes 5, the smallest width is too thick, after reducing the new lines are much more thicker than the reduced ones.
This was a must for me in GoodNotes 4.
Please please please :)