What is his texting has slowed down?

As an AI language model, I don't have access to specific information about anyone's texting habits. However, there could be many reasons why someone's texting has slowed down, such as being busy with work or personal life, a change in priorities, having technical difficulties with their device, or simply losing interest in texting. In any case, the best way to know why someone's texting has slowed down is to ask them directly.