It's too hard to staff places for regular daylight and evening hours let alone overnights. A LOT of servers found new jobs/careers because of the pandemic. Myself included.
Sure, people came back, but losing a big chunk of the workforce you had before really took a toll. And the ones who came back didn't want to do overnights anymore. And I don't blame them. You couldn't drag me back for anything. I get PTO, sick pay and 10 holidays off a year now all paid. 25 years in restaurants and I'm not sad to see any of them go.