text-muted not visible on bg-dark

Prerequisites

• I have searched for duplicate or closed issues
• I have validated any HTML to avoid common problems
• I have read the contributing guidelines

Describe the issue

current release looks good https://getbootstrap.com/docs/5.1/components/navbar/#external-content

current brunch looks bad https://twbs-bootstrap.netlify.app/docs/5.1/components/navbar/#external-content

Reduced test cases

https://getbootstrap.com/docs/5.1/components/navbar/#external-content https://twbs-bootstrap.netlify.app/docs/5.1/components/navbar/#external-content

What operating system(s) are you seeing the problem on?

Windows

What browser(s) are you seeing the problem on?

Chrome, Firefox

What version of Bootstrap are you using?

v5.1.3 and Current main Brunch