I often make use of the memo field within a task, to write down additional information I need for that task, to avoid losing it due to the line length limit in the task list.
Here's a UI problem with the mobile interface (m.toodledo.com):
Click on a task, to go to Task Details.
Click on "All Tasks" to go back.
You are back at the top of your task list! Where you were in the list, is gone. This is frustrating if you have a very long task list and don't remember where you were in the list.
Please add a context restoration feature, to go back cleanly? Ideally, when going back, it would restore as much state as possible, remembering exactly where the user was, when they earlier chose to go forward.
This happens both on phones and on full computers, so I know it's not just a particular browser.