My a71 phone said 15% so I grabbed my charger and when I plugged it in it said 5% then kept going down every second or so to 1% I thought it was going to die but it started charging when it went down to 1%, what a weird bug
This does seem rather strange. Just make sure that you're using a genuine Samsung charger. Also, make sure that your phone's software is updated (Settings > Software update > Download and install). Then, give your phone a quick restart.
