Once inside the ballot tabulator, all votes are anonymous.
Before 2020, challenged ballots would not go into the tabulator, but instead into special envelopes for further processing by the Department of Elections. But in 2020, challenged ballots were added to the tabulator with just identifying numbers on them. So the challenged ballots were counted on election night. Theoretically, if a problem was later found with a challenged vote, the staff could search all the ballots in the tabulator and pull out the challenged one. But in practice this is not going to happen, except maybe in a recount.
Step 3 shows how anyone with an easily forged document can vote as a “regular” voter, which cannot be undone.