Thank you for your question!
Do you mean there appeared an ‘x’ and ‘y’ in the two subtasks?
Did it appear when you added the subtask, or after you went out to other lists and entered this task again?
Are there other subtasks with the same problem?

Look forward to you reply.
Good day!

The last letter of the last word in the title of the subtasks are transferred to the new line.

Spontaneously. A new subtask is not created, just line hanging letter though in the previous line a lot of space.

у вас там кто нибудь говорит по русски?

@Beingmaker Thank you for your description!

Did you come across the problem frequently or just for this task?
Could you please paste us the url of this task ( the url you see when you are in this detailed page of the task) ?

Sorry we don't have people who speaks Russian.

It's frequently.
New task with problem:
http://i.doit.im/home/#/task/dc28fae2-a42c-45d5-9adf-dc12655cacfd

Screen

@Beingmaker Thank you for your telling us!
We've been checked it but not yet found its cause. We'll continue tracking the issue and will tell you when it's fixed.
Thank you!

It's fixed.
Thank you