2Do is constantly using location services and I don’t know how to turn it OFF
You most probably assigned a ’Location’ to a task. Nearby alerts are ON by default (2Do > Settings > Nearby) which means you’ll be alerted for that location when it’s nearby. The location services icon you see doesn’t necessarily mean it’s consuming extra battery. That simply means the application has created geo-fenced location alerts which you’ll be notified of.
You can however find out which task has a location assigned in case you’re not sure. Please launch 2Do and tap ’All’. Then tap on the top search bar and type the following:
This will list all tasks that have a location assigned. You can then remove the location from this task in case you don’t need an alert. Alternatively you can switch Nearby Alerts OFF from 2Do > Settings > Nearby which should allow you to continue tracking the location within 2Do but won’t use location services otherwise when the app isn’t running.