I would say “Don’t use TODOs (in your code) at all”. They are just “broken windows” in your code. If something is a bug and you think that it is important to be fixed - just do it. If you think that something has to be done but it is out of the scope of your current task, note it down somewhere and take ownership of making it happen one way or another. Leaving a comment in your code just puts this responsibility away from you. In my experience this does not work and those type of tasks just pile up.