2019 MacBook Pro battery installation and use issues.

Hello. In my 2019 MacBook Pro, the battery was completely depleted and it is having problems with flashing on the Touch Bar. I can deal with the flashing on the Touch Bar but the depleted battery makes the computer nearly unusable as a laptop. I took it to the Apple Store to see what they could do. Unfortunately, they stated that the computer is now old enough that they don’t service them anymore. I decided to go and get a battery myself on Amazon and, with the help of the instructions which came with the battery and a YouTube video, I was able to successfully replace the battery myself. Let me tell you, it’s not easy. Now when I fully charge the computer and use it on battery power, I get about six hours or so of charge out of it. I run it so that the battery indicator is at about 30% and then I shut the computer down completely to leave overnight. When I turn the computer back on, it starts out at 30% but immediately runs down to 1% and alerts me that it requires to be plugged in. In system settings, the battery health states that it’s normal. I’m wondering what is going on here and if there’s anything anybody thinks I could do to improve performance or at least the computer‘s ability to properly read the charge on the battery. Thank you in advance! Googling various issues with Apple products has many times brought me to the Apple discussions which have been helpful over the years.