Yeah, the black sticker I have seen before.
But as you said, buying a new NES game back in the days - they were not sealed (sometimes with the black sticker).
That's why I am sceptical seeing this. But the seal itself looks good.
Also found this on Heritage Auctions --> https://comics.ha.com/itm/video-games/castlevania-wata-85-ns-no-seal-pal-b-nes-konami-1987-gps/a/122102-13763.s?ic4=GalleryView-ShortDescription-071515
Here it says 'NS' with the motivation that there was no seal to start with.
Is this evidence that this is not real, or could it be differing between difference countries within the EU?