We're making a few behind-the-scenes changes to kudos to make sure the Archive can continue to handle the tremendous number of them (659 million and counting!) that users and guests have left over the years. Kudos will continue to work the same, but there will be a new check in the database to make extra certain duplicate kudos can't be left. This will result in a one-time drop in kudos on works that already have duplicates.
Previously, we relied on the kudos code to make sure a single user or guest could only leave kudos on a given work one time. This worked just fine in most cases, but sometimes a slow connection or quick double press of the kudos button could lead to multiple kudos being recorded.
We'll be adding a constraint at the database level that should prevent this from happening. However, this change will also make any existing duplicates invalid and remove them from the database. This means that if you have received multiple kudos from the same user or guest on one of your works, your kudos total will go down when we deploy this change. For example, if your work has three kudos from the same user, the total number of kudos on the work will drop by two.
We plan to make our changes on Monday, March 16, and we expect some brief downtime at the end. We can't predict for certain what time it will be, but we will do our best to give a heads up on the @AO3_Status Twitter before it happens.