Whatever pinned tab-groups do, it's not well explained, and probably broken.
If they ought to expedite or facilitate guaranteed loading at browser startup, as 'pinned' tabs (not groups) are explained on the browsers marketing page, then congratulations, they don't. The browser instead loads the most recent tabs in reverse chronological order. If you have to many tabs, loading may not happen at all for some portion the tabs in the 'pinned' group.
If they ought to change something visually as the word 'pinning' in Microsoft-Land would suggest, and 'pinned' tabs demonstrate, that is not the case either.
What on earth does a 'pinned' tab group actually do?
