Why do so many Japanese/Korean foods have the P65 warning?

I know this is a general California thing and isn’t specific to Los Angeles but since we have so many Japanese and Korean markets, I figured someone might know.

What am I missing here? Whether it’s ginger, pickles, snacks, or the pictured Kelp, it’s harder to find packaged foods without the P65 warning. Where is all this alleged lead coming from!? As far as I’m aware, I haven’t had lead poisoning or other issues from all these warnings 🤷🏻‍♂️