Nearly all errors from the 2020 Census disproportionately hurt red states, with many undercounted and many blue states overcounted.

Multiple sources, including The American Redistricting Project and NPR, provide data showing specific states with estimated undercounts and overcounts. Notably, several red-leaning states such as Arkansas, Florida, Mississippi, Tennessee, and Texas were undercounted, while some blue-leaning states like Delaware, Hawaii, Massachusetts, Minnesota, New York, Ohio, and Rhode Island were overcounted.thearp.orgthearp.org2020 Census Count Errors & Congressional Apportionmentnpr.orgnpr.org2020 census undercounts by state are released by the Census Bureau : NPR

Commentary and analysis from politically oriented sources emphasize that these census errors disproportionately harmed red states by reducing their congressional seats and electoral college votes while benefiting blue states. These sources argue that the miscounts had tangible political consequences.westernjournal.comwesternjournal.comCNN Analyst: Trump is Right to Point Out 2020 Census 'Errors' Disproportionately...nationandstate.comnationandstate.com2020 Census Errors Affect Elections, Aid Blue States, Hurt Red States+2 more

However, a Brookings article provides a more nuanced view by discussing how census policies and questions could have complex effects on both red and blue states. This suggests that while the general trend of undercounting red states is supported, the full impact of census errors and policies may be more complicated.brookings.edubrookings.eduTrump’s Census policy could boomerang and hurt red states as well as blue states

The evidence is consistent across multiple independent sources that the 2020 Census errors did not affect all states equally and that red states were more likely to be undercounted relative to blue states. This supports the claim's core assertion but also indicates some complexity in the causes and consequences.