It is actually not shifting footer, it is hidden. Once the admob banner is shown, a css class, ‘hide-footer’ would being added to the body, this make the footer being hidden because of ‘display: hidden’ css being applied. My solution is whenever the admob banner being shown, then remove the css class ‘hide-footer’ from the body. Hope it help :). For your info, the ionic version I am using is 0.9.27. So the css class name might be different if u are using different version.
If u wan the debug this problem further, u may try out this approach https://developers.google.com/chrome-developer-tools/docs/remote-debugging