i'm maybe talking cack, but i seem to recall the bodyshop saying to me there is a panel join there? mine was in years back for repairs due to a fair bit of near side damage and i seem to recall saying to the guy when i collected/inspected it what a good job they'd done (we happened to be standing near side rear at the time) and i'm pretty sure he said along lines of 'yeah especially when you consider there's a join here' at which point he pointed to where you've circled. i said 'is it not just one rear panel?' and he shook his head.