TWebBrowser cannot be fullscreen on Android Delphi Application?

Question

I am writing a software that should be work as fullscreen and load a web-page from local server and I set application fullscreen (Form Fullscreen property is true and Project > Option > Version Info > theme is "No title bar").

I am creating TWebBrowser on runtime with button onclick event like below (I tried to create component on design time too);

Var
 WebBrowser : TWebBrowser;
begin
  WebBrowser := TWebBrowser.Create(Self);
  WebBrowser.EnableCaching := False;
  WebBrowser.Align := TAlignLayout.Client;
  WebBrowser.Anchors := [TAnchorKind.akLeft, TAnchorKind.akTop, TAnchorKind.akRight, TAnchorKind.akBottom];
  WebBrowser.Height := ClientForm.Height;
  WebBrowser.Width := ClientForm.Width;
  WebBrowser.Position.X := 0;
  WebBrowser.Position.Y := 0;
  WebBrowser.Name := 'WebBrowser1';
  WebBrowser.Parent := ClientForm;
  WebBrowser.URL := IPAddress+'/web-page-location/';
  WebBrowser.Visible := True;
  WebBrowser.Navigate;
  ClientForm.FullScreen := True;

But when I click the button, while app is switched to fullscreen correctly, there are some gaps (margins) below and above of WebBrowser component.

Interesting part is, when I swipe from down/up screen for status bar/soft keys, gaps are the same sizes of status bar/soft keys sections. So I guess that, problem is not related to App's fullscreen issue, it is more likely TWebBrowser fullscreen capability problem (maybe bug). I've checked many places for the same/similar problems (and tried many things) but there is no any solution yet.

Delphi : 10.1 Berlin
Android Device : v5.1.1

You can find screenshot of problem below:

The gaps are part of Main form of App (I mean If I place any component (like TShape etc) on these positions they are shown correctly. Only TWebBrowser cannot cover these sections) Is there any advice to solve this problem with Delphi way? Thanks