Fat skimming?

Trying to make the chicken Vesuvio soup recipe from the NYT. I used chicken thighs instead of chicken breast as I thought that would taste better. This recipe also has cubed potatoes in it, and I genuinely can’t tell if the white stuff on the top is broken down fat or if the potatoes are slightly crumbling. If it’s fat, what’s the best way to remove? I tried the ice cube and ladle trick without much success and don’t have a fat separated.

I am new to slow cooking so sorry in advance haha