Please reread the articles I posted.
They were Harfoots when they became known to the wider world which I assume was in the second age.
Regardless, they were Harfoots long before the whole Hobbit/Shire thing.
So they are the ancestors of the Hobbits in the Shire.
The hobbits did not become Harfoots at the end of the third age as you asserted in your post with: Harfoots are not ancestral Hobbits - they are one of three “strains” of Hobbits that existed at the end of the Third Age.
That is wrong.
According the articles I posted, which uses info straight from Tolkien’s pen, the Harfoots, Stoors and Fallohides were already separate tribes at their introduction in the lore and then became all one Hobbit tribe during the third age. Not the only way around.
Which was my original point.
The only reason I am arguing this particular point is because when their hobbity-looking selves showed up on-screen as Harfoots, I immediately went internet surfing to find out what the heck was going on and don’t want anyone else thinking it is some weird screw-up like I did when it is not.