C3: Rotated chart with hidden subchart still able to interact with

• C3 version: 0.6.8
• D3 version: 5.7.0
• Browser: Chrome
• OS: Windows

I have a rotated bar graph with long x-tick values. I appears there is a hidden subchart that user can still interact with and zoom in with, even though no subchart or zoom is enabled. See my codepen below:

https://codepen.io/u119102/pen/NOpBmK?editors=1010

If you hover mouse over the middle of the word "January", mouse pointer "+" will show up, pull it down and the graph will zoom in (similar to a subchart functionality)

This does seem trivial in web-page view, but in mobile view, it's in the left side of the page where user tends to scroll with their finger, it can be quite irritating, especially since you cannot zoom all the way back out, without seeing the subchart.

Please let me know if any other information need or it has already been solved.

Thanks.