COVID-19. The inflation that everyone hates was a result of COVID (and other knock-on effects like price gauging), and not all Biden's fault. Biden has been cleaning up after Trump's awful pandemic response, and it's all Biden's fault apparently, so let's give the job back to the guy who messed it all up in the first place.
COVID means everyone needs to work less, that means that every product that is a result of people's work decreases in availability, and thus, increases in cost.
This is a fundamental aspect of any major disruption, including the war in Ukraine, that will drive up prices.
The problem that Democrats and most Liberal governments have is that they just let this happen. The reality of the situation is that the poorer you are, the more of your money goes to necessities, so when the price of necessities rises, the more of your money is lost to inflation. If you only spend 10% of your income on necessities and the rest goes to frivolous things, then you can just cut back on them no big deal, you can shift that money to investments and actually profit off the inflation. But if 90% of your money goes to necessities, than you have no choice and 90% of your money just got less valuable.
Inflation is a frustrating and abstract word that just hides one of that ratchets that keeps rich people rich. They do not pay the costs of inflation (or pay them last). Every single time there is an inflationary event, be it a natural disaster caused by climate change, a war, a pandemic, etc, taxes should immediately rise on the wealthy to pay for it. If they do not, then, it is a tax on the poor and working class that will be hand waved away as "inflation".