I haven't watch Black Widow and have no idea what it is actually so this is not about spoiler or theory. I have this thought just because this two characters give me some feelings they have in common. Maybe someone already has answer to that possibility. But I think it would be interesting if the mysterious new bad guy Death Dealer has some big secret and Shang-Chi movie has more connections to the other parts of MCU. In the trailer, Death Dealer looks like a figure of traditional culture but he also uses some device that is clearly a technical equipment. So his character may be not so simple as it appears. I also wonder if Shang-Chi movie shares some historical background with The Eternals, because it seems both of their trailers feature some ancient period.