One of my first thoughts when I saw this was about screen readers. If searching "Sponsored" in Chrome doesn't match the posts, I'd wager screen readers would just go ahead and try to pronounce all the extra 'S's.
Screen readers obey CSS, this uses CSS to hide all of the additional elements (display: none). Screen readers are also designed to work when text is broken up by other inline elements e.g.:
He<b>llo</b> world
In this case it reads out both the words Sponsored and Public.
> If searching "Sponsored" in Chrome doesn't match the posts
That also worked perfectly fine in Chrome, Firefox, and Edge. Did you scroll enough to render any Sponsored posts?
Well a web browser has to render it correctly, so yes? A screen reader is just another type of browser at this point.
These techniques work because some blockers only support a limited subset of what a full browser can do (namely block resource locations and specific HTML elements).
And rather insignificant to implement. All this protects against is low-effort document scraping. If they randomized it somehow, that would be a little harder to defeat.
