According to @KobeissiLetter, Nvidia has announced that the US government has indefinitely banned the sale of its H20 chips to China, resulting in a projected $5.5 billion impact on their Q1 earnings. Consequently, Nvidia's stock has dropped over 5% following this announcement. This development presents significant implications for traders, especially those holding or considering positions in Nvidia shares, as the ban could affect Nvidia's revenue streams and market performance in the immediate future.