I have to say I love the concept, and I'm very happy with my brand new tabs on the side.
That said I did find a bug and I have some performance problems to report, but it's not clear to me where I can report a bug for a particular experiment.
It looks like the feedback button wants me to fill out a whole satisfaction survey, and "File in issue" takes me to the test pilot github, which seems to be about the Test Pilot program in general.
Is there a better place to report bugs?