Max Tani, reporting for Semafor:

On Wednesday, Instagram parent company Meta introduced Threads, a text-based companion to Instagram that resembles Twitter and other text-based social platforms. Just hours later, a lawyer for Twitter, Alex Spiro, sent a letter to Meta CEO Mark Zuckerberg accusing the company of engaging in “systematic, willful, and unlawful misappropriation of Twitter’s trade secrets and other intellectual property.”

[...]

Spiro accused Meta of hiring dozens of former Twitter employees who “had and continue to have access to Twitter’s trade secrets and other highly confidential information.”

He also alleged that Meta assigned those employees to develop “Meta’s copycat ‘Threads’ app with the specific intent that they use Twitter’s trade secrets and other intellectual property in order to accelerate the development of Meta’s competing app, in violation of both state and federal law as well as those employees’ ongoing obligations to Twitter.”

[...]

Andy Stone, Meta’s communications director, told Semafor that Twitter’s accusations are baseless. “No one on the Threads engineering team is a former Twitter employee — that’s just not a thing,” he said.

Did Twitter overlook the fact that Meta's platforms have a larger userbase and more engineers than Twitter? Furthermore, even if ex-Twitter employees contributed to Threads, Elon Musk terminated their employment, giving them the opportunity to join a rival company.

The crux of this letter is that Musk perceives Threads as a threat and is envious of the extensive media coverage it is receiving, prompting him to lash out.