A voltage issue that discharges the battery from around 40% to 10% in seconds?
Yes, because it doesn't actually goes from 40 to 10% in seconds (which isn't really possible anyway) but the voltage isn't stable which makes any battery readout do weird things because they measure battery by partly looking at voltage. Which is why it can go from 40 to 10 and then for example immediately back to 80 when you plug it in a charger.