This is exactly it. This is a second order effect of the pandemic flight, not a "restaurant" thing at all. People facing long term unemployment/underemployment over the past year had huge incentives to "move back home" (or wherever) to places with lower cost of living.

And who feels that pressure the most? Service workers, who had jobs in the cities, sure, but didn't reap any of the economic benefits of all that urban wealth concentration. They're overrepresented in the population who fled, which means their jobs are now underserved.

Long term, this will probably just be viewed as a correction to a few overpopulated urban cores. We'll find equilibrium again, though not at the same state as before.

But regardless, the fix here is the same: pay more for the jobs and you'll find people willing to do them.