Had the same, but got timeouted for every run

Be careful, list is a class in Python.
A better to use list_ or an explicit name.

This code crashed my code editor for large n.
Appending to a list, then summing, requires all entries to be saved in memory.
This causes a memory overflow crash for very large n.

But what if n=0?

I have a similar solution, with the variation that list lengths are verified during each iteration, reducing execution time becuase it does not iterate through the entire list unless necessary

Knowing that the tests could include some long lists, could it be worth testing the length of the even and odd lists as you go along?
You could have your outlier in the first three items, and save having to iterate the rest.

Mine too.