If this was just people who drowned while swimming or boating, it just wouldn’t make sense that the wash-ups keep being feet, and only feet. What’s happening to the hands, for example?
I also saw the TV special as in post #6. The tennis shoes float the feet to the surface. Other limbs or feet without the tennis shoe don’t float up.
One of the feet was ID’d to a despondent person, no foul play indicated.