Spike in Burndown chart

[Kanwar Narania]

We have created a UAT board for our project wherein once a story has gone through the Active Sprint, it goes to the UAT board.

However, once the status is changed for the story to appear in the UAT board, there is a spike in the burndown chart again.

We want to keep the Active Sprint and the burndown chart separate from the UAT board. Is there a better way of doing this?