If these unemployment benefits were paid out UBI-style, regardless of current employment, there wouldn't be a disincentive to find work.
I think your new marginal rate only applies to anything over the limit that bumped you into a new tax bracket, so I don’t think this is right. A raise always gets you more money.
The exception being if it bumps you out of the government assisted healthcare bracket. Then, a raise could indeed be a loss.
Edit: I thought you were talking about income tax, but you might have been talking about business subsidies, which I know nothing about.
They might either go out of business or automate those roles if they can't afford to pay blue collar workers a living wage. I'm not a socialist, but some business do rip off low income workers. So they might as well cease to exist if they can't find workers to rip off, instead of claiming that people are lazy.