When the iOS keyboard opens within your app (for example, when an input box is tapped) on a mobile device, the way that Apple moves the layout around makes it hard for the Bubble engine to understand how to draw fixed position Group Focus elements. As a result, you may notice that these elements are displayed in unexpected places on mobile devices.
Since this occurs on the mobile browser level, there's no native solution for this behavior in Bubble.
To prevent this, we recommend using responsive design to determine the position and behavior for this element for mobile devices. For more information on the Group Focus element, check out our manual entry here.