Because relative prices are beginning to normalize in USD.
It's a pretty complicated topic that economists can explain better, but basically, prices in USD were artificially kept low due to an artificial official exchange rate, which drained the country's Central Bank reserves. Additionally, the national government pressured supermarkets and various companies to maintain low prices in exchange for allowing them to import at the official exchange rate.
When Milei's administration took over, they devalued the official exchange rate from $350 to $800, causing prices to skyrocket. They also removed price controls and are gradually lifting capital controls and regulations. The new exchange rate, economic reforms, and pro-market government have fostered more trust, reduced economic risk, and increased USD reserves in the Central Bank.
Thus, despite prices rising in pesos, the exchange rate remained stable, resulting in higher prices in USD, aligning with the real international prices of goods and services.
Salaries still haven't caught up, but it's expected that they'll begin to recover by the end of the year.