Country flags can be versatile in terms of their proportions, colours, symbols and overall design.
Each symbol, color or the proportion represents something deeper. Every country flag has an underlying meaning to it which often dictates it’s ideology and values. When it comes to shapes and symbols, many flags feature a sun, moon or a star/stars on them. This also includes circles. While some country flags feature a circle like that of Japan and Bangladesh which are prominent, they reinforce a unique image about the nation. While each circle in a flag would have a different meaning varying from each country, many have religious, mythical, and social reasons for featuring it.
Here’s a list of all the country flags with just one circle.