I've been facing a really annoying battery issue with my 16 inch 2019 MacBook Pro for a couple of days. After I charge it for a while and then unplug it, the estimated battery life drops to 6 hours (normally it is 11-12) when watching YouTube videos. It doesn't change even if I close all the programs and do nothing on the computer. After a couple hours of using it, the battery life increases to its normal level. For example, as I'm writing this post, the battery life went back to normal 1 hour after charging it. Also the overall temperature of the laptop increases by 5-10 degrees during this process. However the battery health is shown "normal". What should I do?