It will never show an consistent number. The way Activitypub operates is "you see what you're subscribed to", and that occurs in a technical/political sense of "these instances have agreed to federate", and in many cases they don't federate everything that happens. So if someone on instance A upvotes something posted on instance B, but instance C is not subscribed to instance A, A and B will see the upvote, C won't.

You don't have to give up on your clout-chasing dreams, but the numbers won't tell the whole story.