Battery problem

Hello,

on 16.01.2021 I bough iPhone 12 mini 64 GB from Technopolis in Sofia, Bulgaria.

When I turned on the phone the battery was 10% and I charged the phone around 4 hours - the battery was fully charge - 100%.

I made the settings of my personal profile. The battery was 94%, when I turned off the telephone. The hour was around 22:00 PM. In the morning around 07:00 AM when I started to use the phone again the battery was already 34%.

So, till today I have to charge the phone 3 times in order to use it normally.

It is not normal for new phone and these prices to have home phone, but not mobile one.

What I can do in this case?

Thank you for your fast reply,

Best regards,

Nely Petkova