I will tell you about my experience about svmsung m31 I bought this mobile on 12th may 2020 from Amazon, so first of all I will suggest you to not to buy smartphone of high cost from Amazon because the days to have a policy in 10 day return but the do not take care of there customer and says lie to there customer
Now I come to this svmsung m31 this company says that this smartphone will fully charge in 2hour and 40 minute but it took minume 8 hours to get full charge,
So I must says to not by this product
If these pice only have this problem then company will contact me and tell me appropriate solution
I face this problem when I run this mobile for some time and then put this for charging then it took 8 hour but it charge fast at morning time because I cannot use it holl night
I would recommend you to perform "Battery calibration" for once on your phone. The thing which you'll have to do is to discharge your phone fully until it gets switched/power off by itself and then charging it fully from 0% to 100% for once. It may help you.