In 10.9, I've noticed that if I create Arcade expressions within a web map, the resulting web map item page has a ton of extraneous text shown in the "Layers" section of the web map. It doesn't seem to affect the web map itself, but is there any reason for this extra text? The extra text seems to take on whatever the web map item name is, in this case, 'test'.
The screenshot below is an example.
Below is a screenshot of the dev tools. This is another web map that has the same issue at 10.9. The layers above the green line are actual sub layers within the map service. I have no clue what the layers are below the green line, or where they came from. The elements below the green line all take on the name of the web map.