This happened in Roanoke, which is left leaning. Republicans are going all out to cheat in this election.
Edit: Here is the law on tampering with ballots in Virginia. Class 5 felony
https://law.lis.virginia.gov/vacode/title24.2/chapter10/section24.2-1009/
For mail-in, you don’t sign the ballot itself. You sign the envelope, which is used to validate / track who voted, but is then separated from the actual ballot before counting so there’s no way to track who you voted for.