I use the latest Joomla 4 with Kunena 184.108.40.206 and the NTS Kay template in the latest version (download today).
Unfortunately I have a problem with the Kunena menu when I am already in the forum.
If I click from my website into the forum, I see the category view (that's how it should be).
Link to it is:
If I am then in the forum and click on the button in the menu "Index", so I see as hover effect below in the status bar also