My iPhone 5s keeping turning off at 100%

I just replaced the battery 6 months ago (battery said it lasted a 3 years) and now every time I use it for more then 3mim without the charger it will turn off. Doesn’t matter the percent and when it does turn off I will plug it in using my wireless charger and it will turn back on with the same amount of battery as when it turned off. And it is not restarting it says low battery with the charger icon so. I need to fix this soon I think it is the battery but this phones isn’t very much anymore. Idk help pls I typed this on my iPhone that is broken soo.