Just below here you still hide or remove the old page before the new page has a chance to appear. You will still get a moment without anything shown on screen. I reckon the new page visibility and optional animation should happen before old page handling.

The behaviour in the PR is the same as the old behaviour. I thought about this "moment without anything shown on screen" but I suspected that the alternative would be that both pages will be on top of one another and it will look weird. I tested now and indeed it looks really bad. I (subjectively) didn't find the split second between fading the old page out and adding the new page to be disturbing at all.

Looking at the code prior to #19094 it does look to me that both pages are visible prior to animation and old page is hidden or removed after completion of either new page animation when navigating forward or exit animation when going back.

I'll try to get you videos to showcase the difference.

            switch (e.NavigationMode)
			{
				case NavigationMode.Forward:
				case NavigationMode.New:
				case NavigationMode.Refresh:
					_pageStack.Children.Add(newPage);
					if (GetIsAnimated(newEntry))
					{
						await newPage.AnimateAsync(GetEnterAnimation());
						newPage.ClearAnimation();
					}
					if (oldPage is not null)
					{
						if (FeatureConfiguration.NativeFramePresenter.AndroidUnloadInactivePages)
						{
							_pageStack.Children.Remove(oldPage);
						}
						else
						{
							oldPage.Visibility = Visibility.Collapsed;
						}
					}
					break;
				case NavigationMode.Back:
					if (FeatureConfiguration.NativeFramePresenter.AndroidUnloadInactivePages)
					{
						_pageStack.Children.Insert(0, newPage);
					}
					else
					{
						newPage.Visibility = Visibility.Visible;
					}
					if (GetIsAnimated(oldEntry))
					{
						await oldPage.AnimateAsync(GetExitAnimation());
						oldPage.ClearAnimation();
					}

					if (oldPage != null)
					{
						_pageStack.Children.Remove(oldPage);
					}
[...]

					break;
			}

Here is behavior on 5.6.70

And then previous behavior in 5.6.33

Thanks for the videos. I missed that the old behaviour when going back was inserting the new page below the old one. I still think it's problematic with pages that don't have a background (i.e. mostly transparent) because you'll see the intersection of both pages but this scenario is more important so fair enough.

Thank you, that should fix it :)