Could you please cite your source?

It’s wholly anecdote from decades of experience. AFAIK, there have been no peer reviewed scientific studies about this. But there should be. It would be interesting to research why it is that testers and bug report contributors are generally widely regarded as needy and demanding of favors. That’s not Debian specific. It’s FOSS wide.

The public perception is that devs are the sole contributors and testers are perceived as tasking the devs for their own personal gain. It impacts software quality because I often encounter bug reports that are very old when searching for prior reports of bugs I discover.

A project that effectively promotes good quality makes it very easy to submit bug reports anonymously, without imposing much of an obsticle, so that bug submissions are not disouraged and so everyone has good awareness of the bug history. Debian has been good on this, which is why Debian is a relatively high-quality project. But they are slipping amid the fight against spam and bots.

Where are they saying this?

IRC

Are they actually treating connections from Tor exit nodes or Torbrowser differently?

Yes. It is no longer possible to submit bugs over Tor, and bugs.debian.org quietly drops packets if the user’s user agent is not what they want.