battery percentage is not increasing but shows that it is charging

Hello,

Check the charging port for lint or other debris and see this:

If your iPhone, iPad, or iPod touch won‘t charge

Also check the battery health:

iPhone Battery and Performance

If it is below 80%, consider a battery replacement:

iPhone Battery & Power Repair

Good luck.

My guess is that you didn't use an authorized Apple repair location and got a fake battery installed.