The trend (Position Trend, Traffic Index Trend) shows the development of KPIs. The development always refers to the selected points in time. If no specific points in time are selected, the results of the most recent analysis are compared with the results of the previous analysis. This is the basis for the trend.
In the example below you can see, that a keyword has appeared new in the rankings and thus increases the traffic index by 3200 (highlighted in green).
Another keyword has moved down one position and thus loses Traffic Index (red background).
Screenshot Search Experience > Organic Rankings Table