Bug: btn-link box-shadow visible on focus

[bodydisplaynone]

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

I just noticed a bug on Bootstrap 4.6 where the buttons scss is missing the box-shadow: 0 declaration for btn-link.

BS 4:

BS 4.6

This causes a weird button outline when leaving or toggling the button in :focus state.

Reduced test cases

https://codepen.io/team/bootstrap/pen/yLabNQL

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

Windows

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

No response

What version of Bootstrap are you using?

4.6

[mdo]

Not a bug: #30036.