Harris' or Harris's? Apostrophe battle brewing among grammar geeks

The selection of Tim Walz as Kamala Harris' running mate ignited a debate on possessive proper nouns ending in 'S'. Discussions arose over whether it should be 'Harris'' or 'Harris's'. Different style guides offer varying rules. Linguists like Timothy Pulju foresee 'Harris's' becoming the dominant form, although current usage varies.