If everyone raises wages, they have to raise prices. For the restaurant, this means they have to charge more for the same service, and they have to pay more for their supply chain (because they also increased their prices).
For the worker, that means they will pay more for things and services they need/want, because every other business will suffer from the same issues and be forced to raise their prices.
All this to say, the worker's purchasing power decreases if everyone raises wages, and that is the definition of inflation.