Moving multiple Safari tabs from one group to another.
I see there isnt an answer for this which is beyond belief, but I found a way.
Long press one website then while holding it select multiple pages till they are grouped together, while holding them, press the current tab group at the bottom, select the tab group you would like to move them to (it will open up the tab group you selected) and just drop them in the new tab group.
iPhone 14 Pro