>It looks like it started to plummet in April 2022, which was on Biden's watch. It apparently was in response to supply chain shocks spiking oil prices due to the start of the war in Ukraine.

it wasn't simply supply chain shocks, it was supply chain shocks in a time of rampant inflation caused by the endless stimulus checks and programs after Covid.

Supply chain shocks cause "legitimate" price increases, it's not "too many dollars chasing too few goods", rather the value of each dollar simply doesn't stretch as far any more, and while trying to hold the line on prices is a fool's errand, trying to make that case to the public in a time of rampant inflation is not going to succeed either