Summary: Python's datetime library has several pitfalls, including issues with naïve vs. aware datetimes, DST handling, ambiguities, and equality comparisons. Third-party libraries like Arrow, Pendulum, DateType, and Heliclockter address some of these but not all. A new library has been developed to provide distinct classes for various datetime use cases, improve DST handling, and avoid silent failures caused by non-existent or ambiguous date-times.
https://dev.arie.bovenberg.net/blog/python-datetime-pitfalls/