How is lowering taxes “socialist”?

In the current leadership contest for the position of leader of the UK's Conservative party, one of the differences between the two candidates is that Liz Truss is promising to lower taxes while Rishi Sunak is not (at least not now). Sunak accused his rival of having a "socialist" plan because of her desire to lower taxes:

This something-for-nothing economics isn’t Conservative. It’s socialism.

How does that make sense? Socialism is all about a strong state with high taxes providing a lot of free services to its citizens. It is usually the parties that are right-of-center, such as the Conservatives in the case of the UK, who instead want to lower taxes and reduce public spending.

I would understand a conservative politician calling the raising of taxes "socialist", but lowering them? Is there some definition of Socialism that would allow calling the lowering of taxes a socialist policy?