I recognize that you have to try something. I'm not going to try to provide comprehensive feedback. Rather, I'd like to offer some narrow feedback on one specific issue:
I do not like that the label for the classic experience is "Troubleshooting / Debugging". That sends the wrong signal. From my perspective, the primary purpose of Stack Overflow is an archive of knowledge that will be useful to others. That primarily means questions about how to solve practical problems. Stack Overflow also accepts troubleshooting/debugging questions, but a bit reluctantly, and that is arguably a bit of a compromise, because those questions are less frequently useful to anyone other than the original poster. Spotlighting troubleshooting and debugging as if they are the central focus or purpose of the classical experience seems harmful to the site.
I ask that you replace "Troubleshooting / Debugging" with something else, e.g., "Programming problem" or "How-to" or "Knowledge" or "Knowledge Library".
Please, as a baseline, do no harm to the classical experience."