I think it's mainly the economy and many democrats having this almost Trump like blinding spot on the issue. Let us imagine that Trump won in 2020. We'd have the same supply chain/demand/China/Russia/etc problems today, meaning inflation would still be high. Just as it is in the rest of the world (but lower here, I might add). Beyond whatever gimmicks Trump may try to fix an issue has no real power to fix, most of his economic messaging would boil down to gloating about how amazing the jobs market is, how fast the labor market rebounded, most jobs in decades etc etc...basically, what Biden and the WH have done. And the results wouldn't be pretty either.
I'm sure Trump would find someone or something to blame all this on, and spread his message across his base effectively. Wouldn't work with normal voters but true believers would be ready to vote. Frankly, just as democrat true believers are ready to vote based on a variety of non-economic issues (democracy, climate change, etc).
Dems have wanted to talk about anything except inflation. I get it. From my professional view I understand this is largely about global events and the Fed. Laymen don't understand that, nor would I expect/demand them to. It's a game of musical chairs and sometimes you gotta sit in the chair full of shit. But the worse thing you could do is pretend none of this is happening, and it doesn't matter even if it is happening. I think preventing anti-democracy candidates from taking office is important but if I was a struggling mom trying to afford food/rent/gas, and too ugly to have my own Only Fans...sure I'd probably be considering my voting options right now.