Poll workers will always be the ones making the final call for rejection of a voters ballot.
I can see AI being used for high speed scanning and recognition. More than a few states are using image capture from multiple sources (years of drivers license signatures, voter registration signatures) etc. They are not comparing - for the most part - one signature on one form as signatgures change over time. Sometime someone may sign something as "World Watcher", another time as "World A. Watcher", another time as "World Andrew Watcher". AI systems can take multiple "aged" and variations and determine a probability of match.
If an AI system "passes" a ballot it proceeds, but you can bet that if an AI system rejects a ballot it will go humans (plural on purpose) for review to accept or reject under strict quidlines, if that human rejects it will typically go require an Election Supervisor for final rejection.
WW