You put quote marks in your text blocks.
The text blocks act as quotes already.
Remove them.
Also, you might need to use the newer JSON decode with dictionaries block instead of that old list oriented JSON decode block.
the core of your onion is losing the list of points because the list is too local. Init the point list before entering the loop over the markers, to allow the points to build up .
That innermost Add Item to List block might be adding to the wrong list.
We would need to see a sample JSON route response content to judge the nesting right.
If you get tired of adding onion layers to your local variable init blocks, you can use the blue mutator button to add ladder rungs.