Interface redesign was a disaster.
Everything is in this nasty blue-grey-ish color not matching system one.
Also lack of separators and following blindly flat design philosophy makes usability much worse.
Opera 58 is the last usable version on macOS.
For those who forget how consistent and usable interface looks like, here is screenshot:
So why you are now forcing this?
This looks like prosthetic arm on macOS. It matches literally nothing. It's frankenstein of Windows 10 flat decorations combined with random color picked by throwing darts at pigeons. So please - add "native OS style" besides your light/dark themes to make it more consistent. Thanks!