To understand the shift in tone that has taken place in Silicon Valley in recent months, look no further than Mark Zuckerberg’s declaration in February that 2023 would be the “year of efficiency”. It is hardly the kind of language to set the pulse racing—unless you are an employee on the receiving end of it. On March 14th Meta, the tech giant Mr Zuckerberg runs, announced it would fire 10,000 staff—on top of the 11,000 it laid off…