I didn’t vote in 2020 and it says I did, or it says I’m red-leaning when I’m definitely blue, or whatever.
Realistically they can’t know who you voted for in the past. That you voted is public record, what ballots were voted is public record, but not a connection between voter and ballot. So how you lean is basically a guess based on information they could have (given what it says about me I’m guessing that lack of party affiliation and being in an extremely red state (I used to vote a mixed ticket, but solid blue since 2018 on the grounds that anyone affiliating themselves with the same party that could nominate Trump doesn’t deserve my vote) are the main factors that drove the assumptions about my leanings that it provided.
Realistically they can’t know who you voted for in the past. That you voted is public record, what ballots were voted is public record, but not a connection between voter and ballot. So how you lean is basically a guess based on information they could have (given what it says about me I’m guessing that lack of party affiliation and being in an extremely red state (I used to vote a mixed ticket, but solid blue since 2018 on the grounds that anyone affiliating themselves with the same party that could nominate Trump doesn’t deserve my vote) are the main factors that drove the assumptions about my leanings that it provided.