Sometimes it happens that on our site Organic Traffic By Ahrefs is 1000, but in the Ahrefs interface, it is 1100

Please note that traffic data pulled via API is based on the 12-month averages that Ahrefs reports in the Legacy Organic keywords report, while in Organic Keywords they show data based on the 30-day averages.

Also, API data is somehow cached compared to what Ahrefs shows in the user interface. Hence this could be some of the reasons.

Read more: https://help.ahrefs.com/en/articles/1115995-is-organic-traffic-a-monthly-figure-based-on-past-30-days