LONDON (Reuters) – Britain’s advertising watchdog on Tuesday stepped up scrutiny of cryptocurrency ads, ordering more than 50 companies in the industry to tell consumers that digital assets are unregulated and volatile. Cryptocurrencies have soared in popularity during the COVID-19 pandemic, with retail and institutional investors alike flocking to the asset class. But bitcoin and other tokens are mostly unregulated in Britain. Adverts for digital assets, from crypto to non-fungible tokens, have become commonplace in Britain on public transport and at sports events. The Advertising Standards A…