With sexlinks, shell quality will be all over the place as the age. You may want to treat with extra calcium if it isn't already offered on the side or direct dose, but it's likely this is her new norm.
One if my hens had a reproductive infection shortly after she went into lay and once she recovered, her heat tolerance was notably worse than her sisters and her shell quality was all over the place - similar to you rings, or often hard but corrugated as well.
They do not fare well long-term. I've lost all mine over winter this year at 3 years old. All different stuff, lumps, hunger strike, and the third we culled as she was also on hunger strike with signs of organ failure.
With her crop, can you feel any air bubbles in there and how does her breath smell? Sour crop is caused by a yeast infection - I'd you've ever had a sourdough starter, that's what it smells like and it will produce gas bubbles in the crop.
A mild infection may start out as slight puffiness or swelling that is noticeable, even when empty with reduced crop emptying.
It may also be visible in the mouth or around the vent if bad enough and commonly can put them off their food.