Wavelet-decompose doing magic

[Krikor]

Hello All!

Could someone explain to me if what I'm getting is the way the Wavelet-decompose filter should behave?

01- I downloaded an image - https://wallpapercave.com/wp/wp12859845.jpg ;
02- I added an alpha channel to the image layer;
03- I duplicated the layer;
04- Using the Paths tool I traced an outline on part of the image of this new layer;
05- I did Path to selection, inverted the selection and deleted it;

So far, no news, a common sequence.

Then on the layer with the cutout and transparent background I applied the Wavelet-decompose filter ( Filters-Enhance-Wavelet-decompose), default settings.

The issue is that the filter, instead of applying the effect only to the visible and cropped part of the layer (the rhino head), applied the effect as if the crop had not been made and the background had been extracted. 

I don't know if I managed to explain the situation well, so I recorded a short 48-second video trying to show what is happening.

https://i.imgur.com/q2bB4hi.mp4

Next, I created a new image using just the rhino head layer, without the original image layer at the bottom of the layer stack.
I applied the Wavelet-decompose filter and again it resurfaced the original background that I had removed.

Am I just confused or is there something strange about this?

Thx!