While available data confirms that successive legislative sessions break records for racial and ethnic diversity, claims about an entire institution being the most anti-establishment lack precise, quantifiable verification.
The current United States Congress is the most diverse and anti-establishment in history.

119th Congress brings new growth in racial, ethnic diversity to Capitol Hill
Source: pewresearch.org
Key Evidence
Pew Research Center analyses confirm that recent congressional sessions achieve record-setting levels of racial and ethnic diversity among voting members.
Public opinion data shows consistently low approval ratings and voter discontent, but institutional anti-establishment status lacks a standardized historical metric.
What the Evidence Shows
Evaluating the claim requires examining two distinct propositions concerning congressional demographics and political alignment. Data compiled by the Pew Research Center and analyzed by the Congressional Research Service demonstrates that recent legislative bodies achieve record-setting levels of racial and ethnic diversity. Successive terms routinely feature higher numbers of lawmakers identifying as Black, Hispanic, Asian American, or Native American, establishing support for the diversity component of the assertion.pewresearch.orgpewresearch.org119th Congress brings new growth in racial, ethnic diversity to Capitol HillBased on data and research compiled by the Congressional Research Service (CRS) and analyzed by organizations like the Pew Research Center, here is the verified context concerning the demographics and composition of the 119th United States...
jbhe.comjbhe.comThe 119th Congress Is the Most Racially and Ethnically Diverse in U S HistoryRacial and Ethnic Diversity: Data compiled by the Pew Research Center confirms that successive U.S. Congresses have continuously broken records for racial and ethnic diversity For instance, the 119th U.S. Congress featured around 139...
Conversely, labeling a legislative body as anti-establishment introduces an unquantifiable subjective metric without standardized definitions in institutional records. While public opinion surveys frequently document low public approval ratings and widespread anti-incumbent sentiment among voters, these metrics measure popular attitudes toward Congress rather than establishing an objective, historical classification for the institution itself.pewresearch.orgpewresearch.orgSection 1 Congress the Parties and the Anti Incumbent MoodAnti-Incumbent Mood: Voter desire to vote out current members of Congress or a preference for political outsiders who promise to disrupt standard legislative norms Anti-Incumbent Sentiment: Measured via election-cycle surveys asking voters...
pewresearch.orgpewresearch.orgViews of Congress Are Near Record LowsHistorically, unfavorable ratings frequently eclipse 70%, underscoring a deep-seated anti-congressional baseline among voters
Consequently, while the demographic portion of the claim is well-supported by statistical research, the broader assertion remains unverified due to the lack of objective criteria for measuring political establishment status historically.