Battery Life

It's absolutely not a problem.

Batteries degrade over time with usage, that's just how they work. You can expect about a 1% drop per month with average use on an iPhone.

Apple recommends replacing it when it reaches 80%

Here are some tips on maximizing battery life.

https://www.apple.com/batteries/maximizing-performance/

janandamesquita wrote:

I used to have an iPhone 7 plus and it took months for my battery percentage to drop... I guess I'm not lucky then

Thanks for answering tho

Battery health is an estimate and how it updates can be odd sometimes. Such as 100% down to 99% for 10months, then a drop to 96% the next month. There's also a variation in original capacity where yours could have been a bit lower than 100% and then updated quickly.

Apple doesn't guarantee any particular performance for the battery, but provides a nominal rating for 80% battery health at 500 cycles. Some batteries do better or worse, but warranty claims just for premature battery wear can only be made if it's actually under 80% before the expiration of the warranty and before it reaches 500 cycles. There are some conditions where the battery may be defective without showing poor battery health, but your issues seems to only be about that 1% drop.

That's fairly normal. You must have just gotten lucky with the iPhone 7 plus.