Battery Health drainning very fast

i have owned iphone 11 pro from a year . In it only dropped to 96% but after that within 20 days it went all the way down from 96% to 93% within 20 days . I only use the charger provided with box. I don't do gamming or any heavy task on phone . why is this dropping that fast? will it stop or keep going down? i strictly charge phone with orignal charger i never use the car charger or power bank not even wireless charge once in this time. do i need to take some kind of precautions? to avoid draining of battery health that fast