I have a problem with the map chart with overlaid pie charts. The pie charts are cutted on top. It can be reproduced on this example: https://www.highcharts.com/demo/maps/map-pies
All you need to do is zoom-in the map chart, move it up and down and look at the pie charts. This is how it looks on my side:
Note that this problem didn't appear for Highcharts v8. I noticed that while upgrading to v9. The example above also works on v9.
I believe it's a bug and should be fixed.