I don't know if it is exactly the same proverb -- it isn't about objecting to the bear (or boar) shitting in the woods, it is about our ability to infer that the bear shits in the woods even if we have never seen it happen. We know the bear shits, we know the bear lives in the woods, even people who have lived in the city their entire life and have never seen bear shit can infer that the bear shits in the woods.
In context, my intended meaning was that software enshittification works the same way: we don't have to see a particular private equity firm enshittify a particular piece of software to know that they do enshittify software, just as we do not have to see a bear shit in the woods to know that the bear does shit in the woods.