What is the lawsuit filed by federal employees against Elon Musk about?

The National Federation of Federal Employees, a major union representing federal workers, has filed a lawsuit to block Elon Musk and his Department of Government Efficiency team from accessing sensitive IRS records. The union is requesting that a judge review the case before Musk's team is granted access to private IRS data sets. This is one of numerous legal challenges against the Trump administration and Musk's government initiatives, which involve accessing sensitive information and implementing personnel changes across federal agencies.