iPhone 16 Pro battery health drop from 99% to 98% in ten charges

You’re fine.

Battery health is only a calculated estimate based on several other internal values; each having their own measurement error.

Don’t obsess over short-term variations.

Only long-term trends matter.

And a 2% drop in 7+ months of operation is quite good.

So keep doing what you’re doing now.

Gosh, you have had the phone for about 7+ months at this point.

The battery is expected to decline at an average rate of about 1% for every 50 Charge Cycles. Rounding up, your battery has completed above 250 Charge Cycles.

So, it would be normal to expect that the battery has declined about 5% since it was new to a current state of about 95%.

Your battery is doing much better than normal, since it is now at 98% when it really should be at about 95%.

Pat yourself on the back. Maybe send a thank you note to Apple.

And, don't feel that you have to be checking the battery all the time. The battery will do what it will do. It won't help at all to try to babysit the battery.

All that you need to remember about the battery is to replace it when the Battery Health is down to 80%.

That will be a long time from now.