Are backdrops hard to look natural?

This past weekend I did my 2 year olds birthday photos

I don’t pretend to have any skill photographing children, my children are the only ones I plan on ever taking photos of because of the difficulty

But when I was editing my photos I kept feeling like my 2 year old looked flat. I did my best to match the noise on her to the background but it is what it is

Then I noticed a bunch of friends sharing photos they got professionally done of their littles and I noticed these photos have the same “problem.” Especially around the feet I feel like I could tell they subject was a separate layer from the background

I rarely do full body photos on backdrops so it’s not something I’ve ever paid attention to, but is this a common issue when editing photos from a backdrop

Edit for more detail: my set up was a white background with two soft boxes pointed directly at it. I was shooting in a basement so not a lot of light in general

When I edited my daughter’s photos I did separate her from the background to blur the background a bit because my backdrop was really wrinkled. So the edits are a slightly blurred background with that layer at about 50% opacity. I lowered the opacity to maintain some of the natural shadows

From some of the comments it sounds like the issue I’m asking about is more to do with too much light than anything on the back end. But the gaussian blur may have also removed some shadows contributing to the flat feel around the subject