@Lolonois thanks, not sure how to ensure it delivers a constant voltage while writing... however I'm not planning to waste any more time on this matter.
The cards in question is a sandisk 512gb ordered from amazon that i had for years and worked fine in my switch. I got the write error in my arcade and i thought the card was done, so i ordered a new one form Amazon. That card didn't work either... Amazon was good enough to send a second card for free and that one also failed.
Who knows, maybe a voltage issue makes sense, but there's no indication of undervoltage on the machine itself.