Reportedly the rate of failure of absentee voters to properly sign their ballots was exactly the same as it was in 2018 - 0.15%. But in the primary the failure rate was higher, 0.28%.
Signature failures tend to be more common among new absentee voters, yet supposedly due to efforts by parties to cure bad signatures the rates in Georgia stayed exactly the same.
Other states had miraculous improvements in the rate of failure, even with thousands of first time absentee voters.
That data alone is not dispositive, but raises questions.
In many states election litigation regularly includes questions about the validity of absentee ballots based on the identity and processing of the absentee ballots, regardless of the actual ballot.
There were states who used automated machines, and tweeked match parameters to allow more through. There are states where courts said they couldn’t match signatures, and where they hired more people without much training, who wouldn’t know how to match signatures.
But Georgia seems to have done it pretty much right. We don’t want to reject valid votes because people scrawl their signatures, or accept votes that are fraudulent.