I just got an email from vote.org saying the following:
Georgia’s Secretary of State [Brian Kemp] put 53,000 brand new voter registration forms “on hold” based on a controversial exact-matching program that removes voters from the roll based on minor discrepancies on voter registration forms, such as apostrophes being in the wrong places. 70% of these “on hold” voters are African American
Unfortunately the email didn't provide citations.
This time article has even larger numbers.
But through a process that Kemp calls voter roll maintenance and his opponents call voter roll purges, Kemp’s office has cancelled over 1.4 million voter registrations since 2012. Nearly 670,000 registrations were cancelled in 2017 alone.