What should I do when daily a neighbor lets two dogs pee and poop in another neighbor's yard?

If you talk to your neighbor, mention that you saw the dog poop in their yard. Give your neighbor a chance to address it. You can ask them nicely if they need a plastic bag to pick up the poop? I dont see anything wrong in that.

Personally, I'd stay out of it. Do something else to distract yourself. You don't want to be in the middle of a dispute.

Call animal control? People can be rude! Good luck with that!👍