Voter turnout dropped by 8.8% among Democrats but only 3.6% among Republicans in the general elections in such states. If, instead of political party, the data were broken down by racial groups, they found that, compared to whites, voter turnout plummets in those ID states: for Latinos by 8.6%, for African-Americans by 10.8%, and for Asian-Americans by 13.6%.
They also found that those who identify as strong liberals also dropped in turnout by 7.9%, while strong conservatives actually vote at a 4.8% higher rate compared to states without the strict ID laws.
We've know this anecdotally. Now we have some data to back it up. Will it matter to legislators who reject science, ignore facts, and distrust reason? No, but it might make a difference in the courts.