From the Wikipedia entry:

Specific visions for Web3 differ, and the term has been described by Olga Kharif as “hazy”, but they revolve around the idea of decentralization and often incorporate blockchain technologies, such as various cryptocurrencies and non-fungible tokens (NFTs).[5] Kharif has described Web3 as an idea that “would build financial assets, in the form of tokens, into the inner workings of almost anything you do online”.

I don’t want financial assets to be created from almost everything I do online!

So it’s not an official standard. It’s a buzz phrase used by people who wanted to make others think “crypto was next gen”