All tabs open when I select a tab group in the Safari sidebar

When I select a tab group in the Safari sidebar all tabs open. This is very frustrating when I want to switch between them easy and often. Now I must close one tab group before choosing a new one.

Before Tahoe 26.0 you could choose a tab group, it became highlighted and nothing more.

Anyone here that can tell how to do so the tab group only becomes highlighted like before?