To make bug report to Debian on Sid, one must have Debian Sid installation. As quoted here,
Debian Sid is forever doomed to being unstable.
There are no “unstable” full CD or DVD images. Due to the fact that the packages in “unstable” change so quickly
So, can you make a bug report to Debian Sid through Debian BTS on an Ubuntu matter? (Ubuntu is supposed to be based on a mix of Debian Testing and Sid, but it is not a direct Debian Testing or Debian Sid derivative.) Would the Debian developers (even if some also package for Ubuntu) take heed of such a bug report? How can you make use of Debian BTS through Ubuntu? If you are only an Ubuntu user, but never used Debian Sid, how would you know, if that ‘bug’ is a Debian Sid bug?
You can’t just ask users to go ask Debian Sid developers on problems of Ubuntu, can you?