aisbergde short answer: you can't revert back.
Long answer: this has been discussed here, so I recommend you to share your opinions there: https://discuss.flarum.org/d/25844
As for my input (and what I'd suggest) is to just handle old admin style with an extension. It would be theoretically possible, but it will be a tough task to just create an extension that translates all of the modals, new settings and styles back. I really like the new style and it's amazing IMO, but not everyone finds it comfortable to use and I understand that.
As for FreeFlarum, we can't do that because we aren't developers. Sorry, not possible right now.
And as for your case, I do agree with the colors of the dots, which should maybe have an icons inside IMO, similar to what Discord did with the online statuses. You could possibly have a browser extension handling the styles (client-side), at least for the colors of the dots too, if you know a bit of CSS.
