I have the Galaxy A20. I noticed the battery was discharging pretty quick and recharged slow. Up to that point I figured the battery was on its way out since it had been 2-3 years old. I ruled out the charging cable and usb plug. So then I replaced the battery and charging port. The issue is still there. Did a factory reset. Downloaded a few apps (a fraction of what I had before). The charging issue doesn't seem to be a problem anymore but the battery still discharges too fast. Sometimes what will happen is the battery percentage will be at like 89% and start counting down 1% every 30-60 seconds. The phone is not hot and I'm not seeing any programs active. Just now I restarted the phone and I was at 3%. It's like the phone is not updating the battery life. I tried to see what app might be causing the issue through "device care" under settings and it just said "learning usage patterns" and the graph shows a huge drop off in percentage. There were no apps listed under the graph. As far as I know, software is fully updated since I did a factory reset. It's almost like an app is draining the battery and when I wake up the phone it's updating the battery percentage slowly in real time by counting down. If that's the case, it's a very careless software feature for a battery monitor.