Why is my puppy eating so much poo?!

I have a 9 month old hound mix and he has recently gotten realllyy into eating poop 🤢. He’s always gone after goose poop on walks but I’ve noticed a big uptick lately that he will eat other dogs poop, and any other animal poop that’s around. Through a quick Google search I’ve learned it could be anxiety or boredom, but he does it when we are on walks, at the dog park, at other people’s houses playing, etc. so it doesn’t seem like boredom.

Could it be a nutrient deficiency or that he’s hungry? Or is he just a sicko 😅

We’ve trained “leave it” but that seems to go out the window when he’s off leash at the dog park or really outside of the house in general.