I'm troubling with the idea that sometimes Python3 is faster than PyPy and i couldn't find why..

Its is actually frustrating in contests when i submit the same code with PyPy and it doesn't get accepted but with Python3 it gets accepted and i get penalty Deducted.

like this code here : The submission with Python3:

163955071 --> 716ms

The submission with PyPy:

163955090 --> 2152ms

I searched along the codeforces blogs to find a clear answer and i didn't find any.