Microsoft has confirmed that there's an issue with its built-in Twitter feature that could result in unexpected data usage. The issue stems from a Twitter back-end change that has caused Windows Phones to re-download the profile images for Twitter contacts frequently. Twitter is currently transitioning its profile pictures from one server to another, and was discovered the data use problem nearly a week ago and reported it to the software giant.
Microsoft is working to address the issue, but as it's a backend Twitter change the company is limited in how it can best address it. Removing a Twitter account from a Windows Phone will prevent the excessive data use fully until Twitter has completed its server migration in the coming weeks. Microsoft has also implemented a change to only sync Twitter accounts once a day to reduce the impact. If you're worried about excessive data use then you can check the Data Sense application in Windows Phone providing you have enabled the feature. Otherwise, it might be worth checking with your mobile operator to ensure you've not passed your data limit for the month.