This sounds totally untrue, and the reverse is actually accurate. Banks are doubling down on London.
Goldman Sachs just built a new 1 billion pound office while Morgan Stanley is searching for a new office -- in London.
Even Deutsche Bank has committed to a new London office in 2023.
That's just the legacy finance companies, there's also Transferwise and other startups who aren't leaving.
Traditional tech companies are also doubling down on London. Google just built a giant new London office. LinkedIn is building a new London HQ. Netflix is also building a new London office.
It isn't surprising considering the talent available in London as compared to EU countries. Salaries continue to be substantially better in London for tech and finance workers.