I would classify that (from my amateur brain storm, I am
NOT an expert) as a type of hyper keratosis (excessive keratin growth).. possibly with genetic roots.. but also agree not likely life threatening, painful, or worrisome for a layer, or non breeding flock. It's GOOD that you're aware and looking into things when they AREN'T emergent! Maybe you will update us even as she progresses throughout her lifetime.
One of my elder pups has it (hyper keratosis) on the end of her ear lobes according to my vet, it might become painful in the future but is likely a genetic anomaly not relative to or effected by MY husbandry. I could feel some very minor swelling and having treated mange mites in the past wanted to know if that was a VERY subtle indicator.
But I would also consider having a vet possibly do a scraping and look under the microscope to rule out any POSSIBLE parasitic cause, IF you have the resources.
Since no one else is displaying that growth and it isn't a commonly seen condition, while nutritional deficiencies do present here daily.. If THIS does have a nutritional cause in THIS instance.. I would consider it to probably also be genetically influenced like any other number of maladies.
One of the photos in the links eggcessive gave looked like *maybe* a cyst the way it had almost a scab on it. Doesn't quite seem the same as what you're describing or what what I can make out in your photos (my eyes being a limiting factor), but those were still good clues! What I found through that was incredibly informative.. and even though written and studied about in other species.. carries HUGE implications to ME and I will be extrapolating what I can as well from the interesting reads that follow in no specific order and JUST as food for thought..
https://www.usgs.gov/centers/asc/sc...ce_center_objects=0#qt-science_center_objects
https://journals.sagepub.com/doi/pdf/10.1177/0300985812469637
https://www.beautyofbirds.com/beakdeformities.html
Cyst of sorts, genetic dna hiccup, or something injurious like a splinter for easy example that the body has encapsulated.. seems *more* likely to ME than irritation which I would *expect* to look more like a scab or angry than what it looks like to me.. which is a happy little "horn". Noting what I expect doesn't always mean it's so and unexpected things happen ALL the time, thankfully!