Verizon's Oath (the brand that subsumed Yahoo, and owns Engadget) stressed in a response that it had taken efforts to strengthen its security systems since the carrier acquired Yahoo, and that this had nothing to do with the European Union's GDPR (which only just took effect).
The fine is minuscule compared to the US Securities and Exchange Commission's $35 million fine, and it's unlikely to have significant ramifications for the company. However, it does illustrate the scope of the problem. When a hack compromises sensitive information for 500 million people, there will be numerous countries that want restitution.
Source : https://www.engadget.com/2018/06/12/yahoo-faces-uk-fine-over-2014-data-breach/