Buttons in ButtonGroup missing borders when mixed Button types are used

[ggdouglas]

Environment

• Package version(s): 5.13.0
• Browser name and version: Chrome 128

Description

A ButtonGroup that contains different types of buttons (e.g. minimal and outlined) can end up rendering some of the borders on the buttons incorrectly. For example, given the following setup:

<ButtonGroup>
  <Button icon="chevron-left" minimal />
  <Button rightIcon="caret-down" outlined>
    1
  </Button>
  <Button icon="chevron-right" minimal />
</ButtonGroup>

the middle outlined Button will render missing its right border.

Code Sandbox

This bug was introduced in v5.13.0, see before v5.12.x and after v.5.13.x

Possible solution

This issue was likely introduced in #6966. We should handle the case of mixed type buttons in ButtonGroup since it was handled previously.