I learned a lot about eating poo this week. Apparently it’s well-known that rabbits eat their own faeces - or at least the caecotroph variant of droppings. The nutrients it still contains are good for their health. But it wasn’t until recently that we found a species that eats a good amount of any other species' excrement.
A genetic analysis shows that foxes eat dog poo, particularly in environments where there’s not much else out there to eat. Unsurprisingly poop is much easier to hunt than wild prey. Perhaps more surprisingly it has a similar calorific content.
It does potentially add to the risk of disease, including of new pathogens appearing - so I doubt “I’m feeding the foxes” can be considered a valid excuse for not being bothered to pick up any dog faeces you may be responsible for.