Do fishing swivels, rooster tails, etc actually contain lead, or is the warning just a legal catch-all?

I’ve noticed that nearly all fishing swivels or rooster tails or any fishing lure that doesn’t seem to have lead inside, come with a “contains lead” warning, but I’m wondering if that’s actually true or just a general legal precaution (like Prop 65 warnings).

Are swivels, lures that don’t seem to contain lead, etc. typically made with lead, or is this just a blanket disclaimer?