Maybe they could seriously claim carbon reduction if they had an optimized logistics network like Amazon. Otherwise they don't really know how merchants handle and deliver their wares.
It's obviously utter nonsense. No serious and/or somewhat intelligent person could interpret said figure to have any useful meaning or need this explained to them. It's just plain bullshit.
So I take it you're not a serious or intelligent person if you can't describe what you find "cringe" about a "carbon removed" statistic. Perhaps you should ask yourself why such a simple statistic bothers you so much.
No carbon has been removed from anywhere. It's just made up. It's as simple as that.
Shopify will quite literally remove the carbon from the air via the Direct Air Capture plants that they've purchased [1]. They're not saying "hey buy from us and we won't knock down a tree," they're literally pulling carbon from the air via DACs.