It’s strange they claim the pans need to be seasoned. As anyone who’s used carbon steel outside of a commercial kitchen where it’s used on gas heat daily with lots of high fat dishes to keep them shiny and dark, at some point it will lose bits of seasoning at home. Between variety of dishes, damage from cooking utensils, or just the act of not washing it after a late night dinner until the morning. Carbon steel seasoning is a delicate spring flower, and I don’t think most people are OCD enough to immediately reseason it after use if they’ve used the pan for over a year and the novelty of seasoning is over. Health concern? Maybe. Health issue? Likely not compared to the massive amount of environmental toxins whatever you cook in the pan is full of. Not something I’m going to lose sleep over.
It’s basically legalese for “please don’t return them. Your pans are the same pans under the recall but we’re not legally obligated to recall them”. I can’t imagine the feed stock for outside the EU is any different.
That being said, while 0.2% doesn’t sound like a small amount by steel standards (there isn’t a carbon steel standard, but it’s probably 1% carbon on the top end), arsenic is pretty much universally bad for steel properties. I’d expect the impacted pans to both be more brittle and corrode faster when you inevitably do damage your seasoning before you fix it.