He's a lot more right wing economically than Johnson.
I think a lot of his support comes from being the man in position when all those furlough payments went out, but he was apparently the one in cabinet arguing for them to be lower and end sooner. He's got a bit of credibility recently by suggesting Truss's plans were batshit crazy, but that hardly makes him an economic genius.
Boris Johnson was an awful person, and an awful PM, but his desire to be loved meant that the crueller aspects of the Tory party were kept partly in check. I suspect we'll simply see Sunak using the current crisis as an excuse to cut back on public services again.