Similar situation here with a patch of trees. From the About: "The shadows displayed by default are estimates gathered through indirect means like crowd sourci

Similar situation here with a patch of trees. From the About: "The shadows displayed by default are estimates gathered through indirect means like crowd sourcing and low resolution data." Not sure what low resolution data they are using for the trees (I can't imagine mine were crowdsourced given I'm the only house around). Probably not worth it for me but apparently the premium version has more accurate/current data.