Why is iPad Calendar alternating?

Why does the ipad calendar (see photo below) show some events with a colored background, while others only have a colored dot beside them? The dots are almost impossible for me to differentiate between colors, so I would like to make all show the colored background.

HOW do I set this? I’ve tried using different calendars, sharing or not, but none of those make a difference. Still, some are dots and others are background.