People and businesses came out of lockdown with saved money and basically free loans burning holes in their pocket which caused a spike in demand (Least important, probably no longer an issue)
Businesses came out of lockdown with a diminished staff and a ton of new uncertainty (much more important, takes a while to recover for some businesses that are planning production multiple YEARS in advance).
Deglobalization/ U.S. national re-industrialization, started by Trump, continued with Biden, which will increase prices on pretty much everything. This is both a reasonable response to the issue, and makes the issue worse in the short term.
There's a hot war with a major energy producer, Russia, which will increase prices for every product where energy is an input (almost every product).
The biggest manufacturer in the world, China, has randomly been shutting down factories and whole metropolises for weeks at a time for the last several years. We just got a correction in this regard, but it will take time for the supply side of the equation to ramp back up, especially given all of the moving parts and uncertainty outlined above.
Bottom line - lean supply chains function well when everything is stable for a longish period of time and it looks like it will continue to be for a longish period of time. In unstable/uncertain environments, supply chains break down, and supply can't keep up with demand, and the government can't keep handing out free money without causing prices to hyperinflate.