История изменений

    <!-- Variant of {@link #Theme} with no title bar -->
    <style name="Theme.NoTitleBar">
        <item name="windowNoTitle">true</item>
    </style>
    <!-- Variant of {@link #Theme} that has no title bar and no status bar.  This theme
         sets {@link android.R.attr#windowFullscreen} to true.  -->
    <style name="Theme.NoTitleBar.Fullscreen">
        <item name="windowFullscreen">true</item>
        <item name="windowContentOverlay">@null</item>
    </style>
    <!-- No title bar, but Action Mode bars will overlay application content
         instead of pushing it down to make room. -->
    <style name="Theme.NoTitleBar.OverlayActionModes">
        <item name="windowActionModeOverlay">true</item>
    </style>

    <!-- Variant of {@link #Theme} with no title bar -->
    <style name="Theme.NoTitleBar">
        <item name="windowNoTitle">true</item>
    </style>
    <!-- Variant of {@link #Theme} that has no title bar and no status bar.  This theme
         sets {@link android.R.attr#windowFullscreen} to true.  -->
    <style name="Theme.NoTitleBar.Fullscreen">
        <item name="windowFullscreen">true</item>
        <item name="windowContentOverlay">@null</item>
    </style>
    <!-- No title bar, but Action Mode bars will overlay application content
         instead of pushing it down to make room. -->
    <style name="Theme.NoTitleBar.OverlayActionModes">
        <item name="windowActionModeOverlay">true</item>
    </style>

[url=https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/core/res/res/values/themes.xml#446]Тут нашёл[/url], а ты какой вариант использовал?