Bottom line is people vote according to how much they have in their pockets.
Biden has lost much support, and if faced by the guy who keeps omitting 2020 from his resume, focusing on the years that were on the Obama trajectory he rode, many will go to him.
Remember, people are stupid and are more prone to believing what they perceive than their own memories.
A poll in 2013 found that 29 percent of Louisiana Republicans said Obama was responsible for the mess that was the response to Katrina, despite it occuring in 2005, well before he even ran in 2008.
People also blamed him for Bush's Great Recession, and credited Trump for the recovery which occured under Obama.
https://www.nydailynews.com/news/politics/lousiana-republicans-blame-president-obama-hurricane-katrina-response-article-1.1433096