By your assessment, though, it seems the seller's market is not caused by the minimum wage, but by COVID relief packages?
Also, I'm sorry you're getting downvoted. I only downvote if someone goes against community guidelines, and not if I simply disagree with them
I think it is important to distinguish a couple of things.
If there are businesses out there, like maybe McDonalds or Walmart, who are easily able to pay $20 per hour instead of $7.50, and are choosing not to do so because of a desire for even larger profits, then yes, this is evidence of a mild seller's market for labor and also a lack of market savvy on behalf of McDonalds/Walmart.
If those corps are already offering $20 an hour and benefits and still people are not showing up to work, then it is a roaring seller's market for labor, and must in theory be caused by some other external source that is causing laborers to feel $20 is too low. Where are they going, what are they doing? Are they taking the opportunity to pursue a degree? Are they staying at home playing video games? Have they all found a job making $42 an hour talking on the phone at home? We would need the data to answer these questions.
But in the exact case of restaurants, I genuinely think most of them do not have the money. I haven't ever in my life met a restaurant owner who has a stable financial situation with a paid off mortgage, nice car, and 3 kids put through college already having become cardiologists or something like that. But I've met a lot of other people who have done all that. And I've met a lot of restaurant owners too.
I think that all they can afford is $7.50-$12.50 an hour in most cases, with no benefits. And now that city centers have seen a good portion of their residents with lots of disposable income move away, I suspect that most restaurants have lost the financial base that used to support them.
I saw a video of a restaurant owner during the pandemic in NYC who cut his staff from 45 to 3 and was just barely able to pull it together and survive. Was he paying his people more than $15 an hour? Don't know.
Previously people accepted the small amount, but now they aren't because they're (currently still) being paid to stay home in most cases.