A radio button is normally presented as circular control but more recently checkboxes are also being presented with a rounded border making them look like radio buttons.
http://flatlogic.github.io/awesome-bootstrap-checkbox/demo/
We have a UI design company working on a project at the moment and they have done the same thing.
So is a circular checkbox bad UI design?
We use circular "radio" buttons to indicate there's only one choice available in the group.
Square checkboxes are used to indicate that a more flexible entry is allowed (none, one, or several). Individual choices are checked or unchecked.
If you're allowing none, one, or several options, use square checkboxes.
If you're only allowing one option, use a round option/radio button.
Allowing multiple choices for round checkboxes is just plain confusing.
Refer to the Microsoft guidelines for Radio Buttons for further reading.
With a radio button, users make a choice among a set of mutually exclusive, related options. Users can choose one and only one option. Radio buttons are so called because they function like the channel presets on radios.
With a check box, users make a decision between two clearly opposite choices. The check box label indicates the selected state, whereas the meaning of the cleared state must be the unambiguous opposite of the selected state. Consequently, check boxes should be used only to toggle an option on or off or to select or deselect an item.
In short, radio buttons offer a choice of a set of options (you have to listen to one radio station, you can't choose none or many). Checkboxes allow you a yes/no to each of a set of options.
Although Pete is right, to elaborate as to 'why' it is a bad design choice, is that it's simply a standard we're all accustomed to. Everyone will regocnize a set of square boxes instantly as more choices possible/checkboxes, and round ones as radio buttons/one choice.
Swapping these shapes will be confusing, and even if people find out the boxes don't work as normal, they'll still be unsure of whether the site/app is working like it's supposed to.
It may depend on the platform. I (and my colleagues) had the same question, especially after we found out our MAUI app used square checkboxes on Android and round ones on iOS. This is not the default MAUI control but it sheds some light on round checkboxes:
The CheckBox follows the rendering guidelines of the operating system. As a result, on iOS it is visualized as a circle while Android and WinUI display it as a square.
When you open the default Mail app on iOS, and tap the 'Edit' button on the top right, you'll see round checkboxes.
