There was a stark productivity drop every summer when kids were out on summer break. This includes parents with dedicated home offices who had been WFH for many years.
The effect was so predictable that we planned for lower velocity during summer months. It was also common practice for WFH employees to spend more time in the office for more focus during summer months if they lived close enough.
That’s not to say that kids are the biggest WFH productivity killer. IMO the people who struggled most were the young people who thought they could travel around and work remotely because it doesn’t matter where they’re working from. It turns out it’s plainly obvious that they don’t get much work done when they’re away from home. But that’s another story.