Not sure how much any parent or child can reliably talk about the culture at a school changing per se. Even if you had e.g. 3 kids attend a given school across 10-11 years, not clear whether their anecdotes would mean much. I can think of a zillion reasons why that would be the case.
That said, you could take a look at the SOTA, a survey done each year by Andover’s newspaper. The newspaper and survey are student run. The survey itself is anonymous so there’s no way to control for whether or not kids reliably self report. Here’s the most recent: