You should not use charcoal toothpaste to 'whiten' your teeth, as this is not something I recommend doing. Your activities are causing damage to your enamel, which is causing your teeth to become more sensitive, weaker, and more prone to cavities. Additionally, your enamel is being harmed over time.
When utilizing charcoal whiteners, you should avoid using ones that are black in color. While you are rubbing little pebbles against your teeth, you are causing damage to the enamel that covers your teeth. Because of this, they appear whiter for a little length of time. Because of this. This is due to the fact that the top layer of enamel, which was dirty, was scraped away in a rough manner, so exposing the layer that was underneath, which was whiter and brighter. If, on the other hand, you want that enamel to last for as long as possible, you should refrain from destroying it in a strong manner.