We aren't talking about a painting in a private gallery, it's a big object in the middle of the street. If it was actually unauthorized it would be removed, even if the British government respected free speech. If artists could actually place at night their works and not be removed, the streets would be blocked due to the number of statues. This clearly seems to be a sponsored work with typical Banksy marketing, like the work that got half-shredded at its auction.

Regardless of whether the physical placement was authorized or not, my comment still applies regarding the specific content of the message.

Authorization could be done with permits, or just tacitly by the notability of the artist. And while one can kind of do some handwaving and liken the latter dynamic to some mild corruption, that is still nowhere near the level of motivated corruption under fascism. And at this point comments invoking phrases like "established media" and "global bureaucratic regime" have a general thrust of pushing us away from liberal institutions and towards fascism, so I find those appeals quite disingenuous.