Place black-eyed peas in a bowl and add cold water to cover by 4”. Chill 12 hours, then drain.
Whisk red and green peppers, scallions, garlic, oil, Champagne vinegar, malt vinegar, parsley, salt, and black pepper in a medium bowl. Cover and chill vinaigrette at least 4 hours and up to 12 hours.
After beans have finished soaking, cook bacon in a large pot over medium heat, turning occasionally, until brown and fat is rendered (bacon shouldn’t be crisp), 5–7 minutes. Add beans, then carefully add broth and bring to a boil. Reduce heat and simmer, stirring occasionally, until beans are tender, 25–30 minutes; remove bacon. Transfer beans to a large bowl, add vinaigrette, and toss to combine. Chill, tossing occasionally, until cool, about 1 hour.
Do Ahead: Salad can be made 2 days ahead. Cover and keep chilled.