My iPhone battery health 89% in only nine month

That sounds about right. The battery ages with use. It is rated to stay above 80% for 500 full charge cycles, which works out to about a 1% drop for each 25 full charge cycles. Only you know how often you charge it from 0% to 100% (or combinations that add up to 100%, like 50% to 100% twice). I notice that your battery charge is very low. It isn’t good for the battery to let it go too low, you should try not to let it go below 20%. And if it goes to zero you must charge it immediately, as Lithium batteries die if their state of charge goes completely flat. That’s why the iPhone still has some charge left when it shuts down, but not much.

Here’s more information—>When to charge your iPhone or iPad - Apple Community