If Biden loses, part of it will be because unlike Trump and Obama, he is terrible at taking credit for good things that happen under his administration. Biden's mostly been an effective president but he a terrible messenger. You can bet that if Trump wins, he'll take credit when inflation inevitably goes down and that will not be a good look for Democrats.
Inflation is currently low enough that it probably wouldn't go much further down under Trump and his proposed import taxes and deportation of the ag workforce, if enacted, would make prices go up again.
But yes, Biden's administration is bad at capitalizing on these things. It's difficult to do when they don't gain traction in the media ecosystem. Stories about good news don't get clicks and don't get shared on social media, so journalists, media influencers, and news outlets don't have as much incentive to publish them. NGOs and activists are more interested in aesthetics of problems that necessitate their existence than progress on fighting the issues, so they will ignore good news as well. And all of this is assuming that everybody is acting in good faith, which in many cases they aren't.
