It's not left versus right here, but rather fact versus allegation.
Erica Denhoff can speak for her the difference for her photos, but cannot decide it must have been intentional and cannot determine if it was NBC Today that altered them, and she cannot determine for which reasons they were altered.
Again, my digital TV has a "Noise Reduction" setting which similarly smoothes out features. I can select "Low", "Medium" or "High". It doesn't seem unusual that someone along the way adjusted things like color balance, and reduced "noise", and the images of Lia Thomas were probably not the first photos altered in such a way.
No doubt the photos were altered, but we don't know, and Erica Denhoff doesn't know, where in the chain it was decided to reduce the noise, by whom, nor why.