If you’re using personal hotspot loads and heavy gaming and export tasks then this is expected from my experience on my iPhone 12 went down too 92% battery health in 7 months. Due to the excessive heat on the battery, I’ve not been doing this on my iPhone 13 pro and have 100% battery heath since new almost 8 months later so it’s all about keeping the heat off the battery as much as possible. I recommend getting a battery replacement asap at this rate you will need it and don’t do heavy tasks on it and save it for the iPad or MacBook £50 I think for a battery replacement let me know.