Anyway, until recently I had a working (albeit hacky) adblock heuristic for Facebook that did the job. However, sometime today I noticed that my script stopped working.
Upon further inspection, they seem to have gone back to simply embedding the word "Sponsored" in plaintext, making it trivial for userscripts and adblockers to select and remove these elements.
Is it a fluke, or did Facebook just give up fighting adblock?
Was surprised that it's still working now. Generally those don't work after a few days.