Well, they don't last forever, so I recommend you go with supplemental protein. 16% is a minimum protein for egg laying, not an optimal amount.
The nutrient levels given as standards are set by the factory farms. They aren't interested in best health or longer life, but more in maximum...
Just something to consider....
Some people feed their hens layer feed and some go with all flock + oyster shell on the side. Layer is generally lower protein, but has calcium for egg shell development. All Flock is the opposite.
I started in the former camp, but moved to the latter. The...
Can't say as I've never used it. That is something others recommend from experience. I guess some canned (instead of kibble), but you should probably search the site for better answers. I use a high-protein feed and scrambled eggs.
You might want to browse this thread to get an idea of what severe molting looks like. They are not common, but you may run into one of these sooner or later.
Post Your Best (Worst) Chicken Molt Pictures - 2023
That all sounds like a typical molt. She is concentrating resources on growing new feathers. It is rather cold at this time of year, so make sure she has places to stay out of any wind. Also, see if you can get her extra protein (scrambled eggs, cat food, higher protein feed, etc) to help her...