What Does It Mean to Use tabindex=-1 on a type=radio Input Element?

[sb3nder]

What is the issue with the HTML Standard?

It's not immediately clear to me how a radiogroup should behave when one of its radio inputs has tabindex=-1.

Test page: https://codepen.io/sb3nder/pen/pvyGWRK (test 5, test 7)

Blink:

https://github.com/user-attachments/assets/78b6d19d-8260-42dc-837f-d36e6adc0018

Gecko:

https://github.com/user-attachments/assets/c863acf6-22bb-48ae-b31b-0e958b015430

Webkit:

https://github.com/user-attachments/assets/2fcac497-55e0-4aa5-8cd8-0c5dc226e0a0