[material-ui][ButtonGroup] Default Styling has borders, background and text similar colour for contained variant

[dafriz]

Steps to reproduce

Link to live example: (required) , Issue is visible on mui.com example

https://mui.com/material-ui/react-button-group/

Current behavior

In dark theme the background , text and borders are almost all black, in light theme they are almost all white

See screen shot from website v5.15.16

Expected behavior

Previous versions, when you had a variant='contained' you could still see the button and text.

Context

No response

Your environment

Chrome on mac

Search keywords: ButtonGroup

[dafriz]

This issue disappeared from local app and mui.com, possibly was a browser, rather than mui issue.