Perception of the economy is that it is not in a good shape, which is more important than statistics for economy when it comes to people voting. There has been a massive decrease in the spending power (the cost of living) and people are struggling. But, we actually are creating more jobs won't cut it, I am afraid. Yes, it is all over the world, but people won't care.
Is Biden the only one to be blamed for this? Of course not. It has been a problem of various administrations, of all of them since I am alive. Trump fecked up the response to covid, the public debt also increased under him, etc etc, but the perception is that the economy was stronger back then than it is right now. And even more importantly, people who are struggling tend to blame the current administration.
For what is worth, I think that the economy would be better under a Harris administration than under a Trump one. Historically, since Reagan, the Democrat administrations did better for the economy than Republican ones. But the current perception is that the economy is not well, and Harris has been part of this administration.