Habit trackers, are they dangerous?

There is a habit tracker that I would like to use, Habitica. I think it might benefit my habit making, but I don't know how good it is in the privacy matter.

I didn't put anything extremely specific. The most personal thing I put is a "homework" to-do before X day.

Should I stop using the app? Did the information I gave is too personal? Sorry if this seems too paranoic.

don good homework making matter personal privacy tracker trackers