What's up with the Game Review opening moves?

The game review opening moves have been a bit weird, as the Petrov's Defense is classified as "Excellent", instead of a book move, though it is one of the most sound openings throughout chess.

Yeah some of them seem a bit weird... I noticed that too about the Petrov (as well as some other things, but out of all of what are normally book moves that is the most... interesting change to me)

of course an excellent isn't bad, but I don't see why it isn't another book move, especially since some openings stay book moves forever (such as in the Marshall, which I am happy about since I play the Marshall)

As for the question below for the Danish (I don't wanna spam the comments too much), it seems to at least make more sense as... there at least definitely is a difference

The Petrov is something top players frequently even at super-tournaments; the Danish on the other hand isn't bad but definitely isn't meta (from what a relatively low rated player like myself would say about the theory of top-level players)

And what about the Danish Gambit???

I'm not very confused to be honest, just shows which move is the best for the opening.

But they're all supposed to be book moves. The Petrov is one of stockfish's top choices. Go ahead and look at the Benoni, or the Marshall attack, they're not exactly the best options, but are still classified as book moves.

Some openings though, like the Petrov, are pretty much equally as good as their alternative and more mainline moves (in the case of the Petrov, 2...Nc6) and it seems better in some of these positions to keep them as book moves rather than non-best moves (book moves are still considered best accuracy-wise)

The Marshall is actually a 'best option', or at least one of the best

but yeah offbeat-ish openings (some of these aren't offbeat but still aren't engine loved) such as the Alekhine, Pirc, King's Indian Defense (which I play), and even the OWEN'S are book moves! (Whether you are for or against the owen's you at least gotta admit that stockfish hates it, much much more than openings like the Petrov... yes it is a first-move but still... so is 1.f3 and that's not a book move anymore.)

Nevertheless, the Danish is still a very legitimate opening which isn't classified properly.

Bro the Kadas and Grob are book moves 💀

lets not talk about fried liver being classified as brilliant....

That is the stupidest classification I've seen in a while...

https://www.chess.com/practice/master-games/world-championships/e3dcf6ea-d397-11eb-a1d5-236d3c0cbbd4 in the game against a bot (1200) in GM position every best move is book move

There is no "best book move". It is simply one engine's preference. For example, Komodo Dragon prefers d4 over e4. Stockfish prefers e4. What happens if you let them play unattended? 998/1000 draws. Exactly.

Well that one makes a bit more sense than some others (the Petrov for example, and ik I keep talking about the Petrov rather than others like the Danish but it’s because the Petrov is the most clear case that I’ve seen so far) because the Wayward isn’t exactly good. It isn’t terrible either, but it helps Black develop really easily.