I have the same problem. I live in Turkey and bought a Macbook Pro 13” 2019 i5 1.4ghz 8gb ram 128 ssd from Apple Store in the US. It shut down at 15%. I then sent it back to the US and replaced it with a new one. I just got it yesterday and this time this one shuts down at 50% of the battery. Got reaaaally dissappointed. Although I have some hope now after reading this topic that it might be fixed after charging for 8 hours which I haven’t tried yet.
Can anyone share its experience who had this fault and fixed it this way? Did you encounter the same thing afterwards or does it work just normal since then and for a long time?