Microsoft is aware of the issue that customers are facing for Brazil time zone in the Outlook Desktop App. Outlook incorrectly uses the current years’ (2019) time zone rule when expanding the recurrence pattern for calendar items. The application calculates the time for the individual instances meetings should occur regardless of what year the instances themselves actually occur. For example, although it is the year 2019, Outlook will use the 2019 time zone rule to expand a recurring appointment that occurs in the future such as in January, 2020.
Since the 2020 rule for Brazil is different than the 2019 rule (specifically the UTC offset is different in January 2019 vs January 2020), Outlook has a bug where calendar items displayed are off by an hour when looking at the January 2020 calendar. On January 1st, 2020, these calendar items will display correctly since Outlook code will use the correct 2020 rule for calculating the time.
For more details please follow Outlook article : KB4484172
