In Recent -> My summary:

How come the widget for Hours played history, on the monthly view only shows data for the past 2 years? The other widget like Achievements and Games added show data for 6+ years.

I play games using GOG Galaxy 2.0+ for way more than 2 years.

For me, all three widgets have the same start date. They show less than 2 years worth of data, so they don't go back to the first time I started using GOG Galaxy.