Florida ad agency sues Elon Musk's X Corp. over trademark infringement

X Social Media claims X Corp's rebranding from Twitter causes consumer confusion with its services.
Lawsuit alleges X Corp. ignored cease-and-desist letter about infringing on X Social Media's trademark.
X Social Media seeks to block X Corp. from using "X" name and receive damages for lost revenue.
X Corp. recently applied for its own trademarks on the letter "X" commonly used in tech branding.
Case faces challenges due to crowded field of "X" trademarks, professor says.