Duolingo's stock is experiencing a decline, with some reports indicating a significant drop from its peak. The reasons for the decline are unclear, with possible factors including slowing growth metrics, margin pressure, and potentially a recent development involving T-Mobile. The stock's current price has fallen, with various percentages reported, ranging from 5.8% to 7.1% in a single day, and as much as 78% to 80% from its peak.