What is the downside of an I bond?

As a keen observer of the financial markets, I'm always curious about the various investment options available. I'm particularly interested in the I bond, but I'm also aware that every investment has its risks. So, could you elaborate on the potential downsides of investing in an I bond? I'd like to understand the potential for inflation-adjusted returns to underperform, the potential liquidity issues, and any tax implications that might arise from holding an I bond. Additionally, I'm curious to know if there are any limitations on the amount I can invest or if there are any redemption restrictions I should be aware of. I believe it's crucial to have a comprehensive understanding of the risks before making any investment decision.