Demand curve shifted. Basically the average person temporarily has more money due to government stimulus, so vendors increase prices, find that overall profit increased, and keep cranking the dial. It becomes a mad rush between the product manufacturers and the retailers on who can increase the price the fastest to grab that additional profit. The only bastion of sanity is Costco, whose prices seem to increase closer in line with the underlying commodity prices.

You see this in the housing rental in constrained markets. When the minimum wage increases, the landlords can all just increase their rents, and the renters, with high moving costs, just pay. All the landlords do this, and eventually all the minimum wage gain is absorbed by the landlords. Makes me cynical that raising the minimum wage does anything other than drive inflation in the rental market. There are likely better policies to increase the quality of life of the bottom 50% than increasing the minimum wage, but our politicians have that lever, and get votes when they use it.