I've been having this issue for as long as I can remember. I thought it might have just been from my phone or the emulation, but after publishing my app I still see this black rectangle at the bottom of screen, which looks like the status bar.
This happens after I have this in my config.xml
<preference name="android-build-tool" value="gradle" />
<preference name="Fullscreen" value="true" />
<preference name="Orientation" value="portrait" />
Screenshot:
UPDATE
I noticed the bottom black bar goes away if I MINIMIZE the game and click it right back up (weird).
I tried creating a new project and same thing happens once I put the full screen preference in config.xml.
It seems like the top bar transfers to the bottom >_>
Seems that the problem is with defining the dimensions of the canvas. Solved this a while ago so I'm not sure if this is what fixed it:
var c = document.getElementById("canvas1");
var ctx = c.getContext("2d");
var pixelRatio = window.devicePixelRatio || 1; // get pixel ratio of device
c.width = window.screen.width * pixelRatio;
c.height = window.screen.height * pixelRatio;
c.style.width = window.screen.width + 'px';
c.style.height = window.screen.height + 'px';
Also try deleting your index.css file