When switching from the new version to Classic, a box pops up asking why you want to do so. I made a list of my concerns & sent it to them. If enough of us do that, perhaps it will change their minds.
My specific concerns are that in the new version, groups with new posts are not indicated; in Classic they are bolded, making it easy to select which group to review.
In Classic, "mark all as read" is a top line button; in new it's behind 3 dots.
In Classic, within a group, new posts are bolded; new version it's not clear to me if there's any difference between new & old posts.
And of course the lack of or non-functionality of the "reply privately to author" function that is so useful in Classic.
Just for fun, I asked them "What problem are you trying to solve?". Probably a question they haven't considered. OTH, hopefully if they get enough pushback they'll rethink this change.
dougP