Starting on December 29, webhooks using the macro date format "YYYY-MM-dd" to pass dates found that these were being populated as "2020-12-29" rather than "2019-12-29". This is due to Java's SimpleDateFormat class using YYYY to represent the year of the week (with December 29 being part of the first week of 2020).
On December 31, at 1:40pm PST we updated webhook templates system-wide to instead use "yyyy-MM-dd". There are no changes customers need to make at this time.
Attribution, Branch Dashboard & Reporting, and Exports were unaffected. This affected only postbacks/webhooks sent during the time period using YYYY date format (as opposed to yyyy).