Thanks for this first answer,
I implemented Shimmer effect thanks to Renderer.
I created a ShimmerView (Forms), with a ContentView bindable property.
In each renderer, I created native view associated to CustomView (Forms) content.
Set this native view as Content in the ShimmerView (the NAXAM one, for both platforms).
As you can see in screenshot in attachment,
my renderer is working fine.
As soon as I try to use my view (and so associated renderers) in SfTabView.
Renderer is called, but NEVER shimmered. (Second screenshot where there is no shimmering effect).
What in your SfTabView rendering might cause this problem ?
I ONLY have this problem for Android,
iOS is working well WITH or WITHOUT SfTabView.