In the previous versions, a very good resource were brushes that could paint on what was written without obscuring or erasing it, a key to taking notes.

With the new layer function, the pens obscure what was written previously.

Solution

1.- that the first writing layer (by default) is not the background, allowing you to add layers of color underneath

2.- it can also be good to have a highlighter-type pen that does not erase or obscure the above.