If you explore the tyGraph model in edit mode, Power BI desktop, or use older reports you will come across measures suffixed by "KPI." For example, Unique Page Viewers KPI, or Engaged Members KPI.
What does KPI Mean?
KPI is just the POP% measure with an added up or down arrow to give you more obvious context. Usually we drop the KPI term in titles but you may see it in old reports or when editing.
This was just our way of expressing the period over period change with the added up or down (kpi) arrow to the right of the card.
The measure is usually the Pop% with an up or down arrow at the end. POP% stands for "Period Over Period" see this article for details.