There’s some misinformation floating around regarding Lemmy not having a karma system. While many have discovered otherwise, this is for those who may not have.
While it’s not exposed in the Lemmy default user interface, Lemmy does have a fully functional karma system and it is visible in third party clients such as WefWef and Memmy.
Do with that what you will.
I can only speculate, but the number may relate to when the number was fetched or the numbers from a single instance. I know the instances are independent, but rely on a number of bot like “helpers” to pass information between federated instances. I saw an issue come up when .world was scaling and the conversation went into the need to allocate more of these “helpers.” The way the instance is configured to update these stats probably has an impact on what you see in an app.