To me, this appears decently level ground standing on.
Take a straight-edge and place it across the wither highest point and rump highest point...
Measure the distance from back to bottom of that straight edge....depending upon that number could and would impact my making a claim of sway or not.
A article about sways and where it seems study has not been as good as some other ailments, but...the numbers and findings are spoken of.
Click to read on equusmagazine.com
equusmagazine.com
A study at the University of Kentucky says 2 1/2" or more and you have a sway...
I see a stance of sore in a few of the pictures shared too....but can not say why or where from a still photo.
Swaybacks are often said not painful, but look bad to the observer.
Saddle fit can create pain issue so careful consideration and support for the animal is a must.
Exercising to strengthen weakened is important and can improve mobility and guess appearances.
🐴...
jmo...