I am getting two different time offset using US/Eastern pytz timezone.
>>> from pytz import timezone
import datetime
tz = timezone('US/Eastern')
>>> tz.localize(datetime.datetime(2021, 11, 1, 21, 1, 0))
2021-11-01 21:01:00-04:00
>>> tz.localize(datetime.datetime(2020, 11, 1, 21, 1, 0))
2020-11-01 21:01:00-05:00
Why am I getting different time offsets for the same timezones?