It’s likely that your last period was shorter than your typical period length.
Clue calculates your average period length based on data from your last 6 cycles, and then uses this to show light pink period predictions. You can find your average period length statistic in your Analysis Tab.
For example, if you’ve tracked 4 days of period, this shows as red on your Cycle View and Calendar View. But the app knows that your average period is 6 days long, so it shows the light pink prediction on the 5th and 6th day.