Help needed: why some of my posts increase and decrease $$ value?

So I have noticed that some of my posts keep increasing $$ value even though the numbers of upvotes has not changed.

I also noticed that then over time the $$ value dicreased before I could claim the rewards.

Does anyone know why? Am I doing anything wrong?

*** If you find this post interesting you can upvote so I know this is the right direction to take, you can resteem if you think others might benefit or comment to share feedback or constructive criticism ***