My little Leghorns (bantams) as they get older their combs are less (? How do I explain) vertical? They are not so hard with blood pressure. When they feel poorly the comb will get darker, purple-ish and lose the spring it has when they were younger. (Kind of like boobs, they are firmer and higher up when you are a teenager than as a menopausal old bird like me)
If they have a prolonged illness, the comb does not come back to its original shape but color returns. I have one with ascitite (? Spelling) aka water-belly who has been drained twice. Her comb is smaller and floppier than it was but the color came back.
Your girl is very pretty

she has nice little feathers on her face, (mine get a more exposed face when they come around towards a molt and then fill up with face feathers when they molt.) She has a nice wattle and her comb looks good, just a little dry. I see that sometimes in winter, or when they are sick/recovering. I have one completing a molt and her comb is dusty too. I see what you mean about the yellow in the legs & beak.
The color of a chicken can change with age, my RIR will get a different color if they have a heavy molt and the eggs (which are brown) will be paler as they age.
Keep an eye on her belly is my best LH advice... They get liver infections and water-belly. Look for swelling in the abdomen or half made eggs that get stuck on the way out. Those tend to predict issues. Mine don't live long after they stop laying. They take egg breaks when very sick or molting but usually if it doesn't return, they are going to heaven.
They suffer more from cold than others (not enough down feathers is what I tell them, but they won't listen to me ) so if it is cold where you are that may slow the eggs.
I worry the yellow for yours is predictive of a liver problem.
Here is my girl come in due to a bad molt at the worst moment in the cold snap. I agree yours has a more yellow beak. Mine is not laying, hasn't for a little while because of this hard molt, so I don't see a link to egg making/yellow. (her name is Robin-Hood ) she had a forest adventure when she was little.
A 4 yr old laying is going to be hit&miss, there will be breaks... She is more looking for a retirement than babies. I love that yours beats up the rooster if he gets frisky when she does not feel like it. It is a good sign of desire to live.