Working on a big Delphi Firemonkey iOS Project i found out calling TForm Method ShowModal create such cross effects for incalculable situations. Working with UITableViewController for example the created SubForms the bouncing effects are not working anymore correct.
So if you create and show a form with a parent form created with show modal replace it with show Method
myNewForm:=TMyForm.create(self);
myNewForm.ShowModal;
myNewForm.Show;
btw: in iOS projects a showModal Method fit not in the concept from iOS.