So, the next Community Day is on Sunday which really sucks and I just wondered why. First I thought: somewhere, far far away, one person did trouble in a mall, and to avoid that in the future Niantic put the Community Day on a day when malls are closed. But then I thought that those malls are sponsored locations which benefit from events like this.
Then I got a second theory: Niantic surely has some timetable for Ex Raids, so what if there is an Ex Raid sceduled for 24th march and they were forced to move the Community Day?
Well in our town we have no mall to play, so most people are happy about sundays bc some got to work on saturdays but only very few on sundays. So i just think it depends on where u live and how u play in your town