What is Google PageSpeed Insights and what is Lighthouse?
Why have Google’s PageSpeed Insight scores changed so significantly lately?

Let’s start with Google PageSpeed Insights years ago: Google PageSpeed Insights was introduced to make the Internet better. Maybe Google found out a lot of webpages need improvement. At the time Google was right.

So, they invented a great toolset called Google PageSpeed Insights.

At around the same time or later they indicated to the market: A good Google PageSpeed Score will have a better SERP, meaning your web site ranking will improve.

OK, this was a great deal!