People call the company that owns Facebook Meta all the time. Facebook is still called Facebook because they didn’t change Facebook to Meta, they changed The Facebook Company to Meta.

Technically Facebook is still called Facebook, it’s the parent company (IE who owns everything and who is listed on the stock market) that’s now named Meta. However it’s a similar situation to Google and the parent company Alphabet, No one calls google or google connected products Alphabet products because it’s not meant to be what you refer to it as.