Place the cubed potatoes in a large pot and cover with cold water. Bring to a boil over high heat and cook until the potatoes are fork-tender, about 10-15 minutes. Avoid overcooking to prevent the potatoes from becoming mushy.
Drain the cooked potatoes in a colander and allow them to cool. Meanwhile, you can start preparing the dressing and other ingredients.
In a large bowl, whisk together mayonnaise, yellow mustard, chopped sweet pickles or relish, granulated sugar, apple cider vinegar, and garlic powder until well combined.
Gently fold in the cooled potatoes, diced hard-boiled eggs, finely diced green onions, and celery into the dressing until everything is evenly coated.