The Harris-Walz campaign is confusing grammar nerds everywhere

[Igel]

2. Not confused.

A question of stylistic choice and register.

Words ending in /s/ have had the colloquial/educated informal spoken possessive /es/ for many a decade. In my mid-60s, it was normal when I was in grade school even in my dialect's markedly syntactically conservative working class speech. (The many/much distinction was absolute, and even when drunk kids failing English would invariable match Dickens for the use of the English subjunctive. Still can't parse "it's important that he's at the debate tomorrow" and fight to accept it means "it's important that he be at the debate tomorrow." One's fact, one indicates something that evinces doubt as to occurrence and is maybe counterfactual. At 5 I had the subjective mastered.)

The more formal and literary standard hearkens back to long before my birth and just says that the ending of the genitive in English is /s/. It's attested in Chaucer and before, Mallory and after. "Lewis'" where the only indicator of genitive was the pointless and silent marker '--and even that marker is of fairly recent coinage. "John" and "Johns" were unremarkable for hundreds of years of printing.

How conservative your written style is probably matches whether you like open or close punctuation, I'd guess.