Why do people say that the Mona Lisa was the first modern painting?

The Mona Lisa is often regarded as the first modern painting due to its groundbreaking use of techniques such as sfumato, which creates a soft transition between colors and tones, adding depth and realism. Leonardo da vinci's focus on the psychological complexity of the subject and the innovative composition also contributed to its modernity. Additionally, the painting's emphasis on individual expression and its departure from traditional religious themes marked a significant shift in the art world, paving the way for future developments in modern art.