If you look closely, it's at half, or a quarter. It's where the bubbles used to be, but took them out. So now it acts like that bubble is upgraded, but it's actually not. It'll show at half of the bubble though. It's like they put the bubbles inside the other ones, and it acts like that's been upgraded, but you obviously can't upgrade it.
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Side note: Surprising how many people didn't notice that it's at half when it says it's been upgraded and realize that that's just cause it's where the armour upgrade for them would have been.