There is another explanation: If one saves seeds from just one or a few plants, there can be inbred mutations popping up or what is termed “genetic drift”, where genetics, which is not diverse, goes in another direction. My parents, in FL, kept saving seeds from their two plants and the seed’s became less viable and produced fewer pods.
Before you pitch the plants or let them freeze, it’d be worth trying an experiment:
If the plants have Calcium deficiency, all sorts of anomalies can happen. In the evening, spray the foliage down with “Rot Stop”, a Calcium chloride garden spray used to stop blossom end rot. Another, slower method is to take 1 1/2 teaspoons of powdered dolomitic limestone, mix it with one gallon of water and pour it into the soil while swirling to keep the powder suspended. Foliar feeding, days later, with an all-purpose fertilizer, then seaweed will supply any other missing nutrient, e.g. phosphorous.
When I grow Aji Amarillo, I try to grow at least eight plants. The seedlings are further diversified by starting seeds from different years’ harvests. So, in a given year, plants from seeds collected in (e.g.) 2013 and 2019 will be grown and bees mix up the pollen. In the tent, where bees are absent, I grab a small paintbrush and “play bee” in the morning, mixing pollen from all the plants.
Shrinkrap, there are many varieties of Aji amarillo, most with local populations bred for the local climate and production needs. “Escabeche” is the medium-long, fleshy, most common type; the one I grow. I got rid of my “Mirasol” types, as the plants were gigantic (over eight feet in August) with pods spread far apart. Mirasol Aji Amarillo are bred for drying in the sun, which explains the tall, leggy plants. They likely dry on the plants.