Google Brain and Google Research are not DeepMind (an acquired company based in London). Transformers came out on 2017. Last year DeepMind was told to merge with the rest of Google AI (kinda). But it looks like they are still quite independent.
https://en.wikipedia.org/wiki/Google_Brain
https://en.wikipedia.org/wiki/Google_DeepMind
https://research.google/teams/