Battery problem with iPhone SE2

Hello!

Bought an iPhone SE2, days ago. Still don’t have a apple adapter so im using a xiaomi adapter 33w from my previous phone with the cable that came with the iPhone. Bought the phone from a website that sells refurbished phones, and there was a option to buy it with a new battery so thought it will be good to have new battery. The phone came and it look soo good and it’s with 100% battery health. The problem is when I was first charging it, it got stuck at 99% and it didn’t charge to 100%. I decided to unplug it and restart it, and it was 100% instead of 99%(it was still saying “last charged to 99%” in the settings). The battery held good almost all day. And when i was charging it for the second time since i got it it again got stuck at 99%. I didn’t restarted it immediately and was browsing some social media but it didn’t drop from 99% so i restarted it. It showed 100% again and after some more browsing it started to drop finally. After 30 minutes maybe it showed the real drops from browsing before the restart and from 96 it dropped to 88%. So what could the problem be? Not using an apple adapter? Or the replaced battery? Or it’s not calibrated? Should I try with apple charger?