Is it normal for my iPhone 15 Pro with 98% charge after restart shows 100% charge?

My iPhone 15 Pro is one month old. Today I charged up to 98% of the battery, and after some time, I switched off for a minute. After restarting, the battery level showed 100% then I was shocked, and it immediately came down to 99%. Is there any issue with the battery?

[Re-Titled by Moderator]