This is likely the correct way to state things.

Facebook the product is run by a company named Meta. Google the product is run by a company named Google, which is owned by the conglomerate Alphabet. Google is the vast majority of Alphabet, and they share CEO and CFO. So when you talk about Alphabet's finances or stock price, you're mostly just talking about Google but the name Alphabet is correct. However if you're talking about a company doing thing, you're almost certainly talking about one of the subsidiaries.

Eg, "Google made AlphaGo" or "Google's Deepmind made AlphaGo" is incorrect, but "Deepmind made AlphaGo" or "Alphabet's Deepmind made AlphaGo" are correct, while "Alphabet made AlphaGo" is technically correct but unspecific.

It’s a different structure. Google the company still exists and is owned by Alphabet. Its products include Google search and YouTube. There is no longer a company called Facebook; Facebook is a product owned by Meta.

They use this phrasing in the article text:

"four tech giants— Microsoft, Google parent Alphabet, Meta (formerly Facebook ) and Amazon"

So I guess the distinction in their eyes is that Facebook renamed itself whilst Google sold itself to a parent company? Can someone chime in on the legal entities and mechanics used for the two?

Google LLC is a subsidiary of Alphabet Inc. Don’t know about Facebook/Meta though

Facebook was a straight rename to Meta, no parent company or anything.