This is true. HR 5371, the budget bill passed in November 2025 which ended the longest government shutdown in United States history, included writing that allow eight US senators to sue the federal government for at least $500,000 if their data was searched following investigations regarding the January 6th insurrection on the United States Capital. Reliable news outlets have confirmed this, including CBS news which said that the bill would "allow senators to bring lawsuits if federal government enforcement seizes or subpoenas their data without notifying them, with potential damages of $500,000 for each violation."
Specifically from HR 5731, the budget bill says "Any senator whose Senate data, or the Senate data of whose Senate office, has been acquired, subpoenaed, searched, accessed, or disclosed in violation of this section may bring a civil action against the United States if the violation was committed by an officer, employee, or agent of the United States or any Federal department of agency." Notably, this is not specific to investigations regarding the January 6th insurrection, but any investigations in general. The New York times reported that the resolution is retroactive back to 2022, so the eight senators investigated because of January 6th could use this resolution to sue the government as their phone records were subpoenaed as part of the investigation.
Sources:
https://www.nytimes.com/2025/11/10/us/politics/senators-shutdown-smith-phone-searches.html
https://www.congress.gov/bill/119th-congress/house-bill/5371/text#id597ffa9d3bc14112bf4807c045e7b016
https://www.cbsnews.com/news/government-shutdown-senate-lawsuits-500k-january-6/