I have, witnessed it in SRI in the 80s a 4 to 8 band just right along the coast. I told the story here many times but the young bucks thought I was crazy...
The venturi was a joke. Lol but your toilet vent acts a straw basically when high winds blow across it it changes the water level and creates the slosh.
I remember how much people busted my chops about my experience back in the 80s in South County with sound effect snow. There was a 6 to 10 band immediately along the shore inland 5 miles had nada