Probably over a particular period, like the last 24 hours? That means that you've added some, but some others would drop off. Doesn't mean that's right either but could account for it not adding up.
I also remember ages ago, someone saying that they only got counted when upvoted but that could have been wild rumour on the LeoVine
counting only when voted 🤔 don’t think so, must be a wild rumour imo!