Why does the sum of users in a report not add up to the total in Google Analytics?
You should not add the number of users in Google Analytics and the reason is a single user can have multiple sessions (i.e. a user can log in at various times). Nevertheless, every time they visit your site, even if it is the same user, they would be counted as a new user. For more information on this metric please read the following article https://help.analyticsedge.com/article/misunderstood-metrics-users/
This usually happens when you are in the process of verifying the data synced to your warehouse with what you see on the Google Analytics UI.