Tesla did nothing wrong in moving up the deadline, according to a decision by the Securities and Exchange Commission. But some activist shareholders saw it as a deliberate attempt to squelch their efforts to make the company improve its treatment of employees and to add board members who are more willing to stand up to Mr. Musk.

“It was really sneaky,” said Kristin Hull, the chief executive of Nia Impact Capital, a firm in Oakland, Calif., that has previously challenged a Tesla policy requiring employees to resolve complaints of discrimination before an arbitrator rather than in court.

Tejal Patel, the executive director of SOC Investment Group, which represents the interests of labor union pension funds, said the deadline change was “indicative of how Tesla treats its shareholders.”

Tesla did not respond to a request for comment.

Some investors saw signs that Mr. Musk was responsive to some of the shareholder criticism when he announced last week that he would name Linda Yaccarino as chief executive of Twitter, the social media company that Mr. Musk acquired last year. Hiring Ms. Yaccarino could free Mr. Musk to spend more time managing Tesla. Investors have complained that Twitter has distracted Mr. Musk from Tesla at a time when the carmaker faces slackening demand and increased competition, which have led it to cut prices.

Nia Impact and SOC were among eight investment funds and activist groups that last month called on Tesla shareholders to reject the nomination of J.B. Straubel to the company's board. They said Mr. Straubel, who was a senior executive at Tesla for years before leaving to start a battery recycling and materials company in 2019, “is clearly a company insider and not an appropriate choice for a board that already has a dearth of independence.”